LOIS SCHIFF gave herself a special 45th birthday present the other weekend. She finished her second marathon. With three women from her running club to cheer her on, Schiff completed the 26.2-mile Shamrock Marathon at Virginia Beach, something that once seemed an impossibility to her.

When Schiff moved to Washington five years ago, she wasn't a runner. In fact, she'd never run a mile in her life. But with the encouragement of friends who belonged to the Oakton Running Club, she thought she'd give it a whirl. Three years later, she was entered in the Marine Corps Marathon. And then a couple of weeks ago, there she was at the finish line of the Shamrock.

"The moral support of the people you train with makes it easier to cope with the stress and pain of a long race," Schiff says. "When you set a goal such as running a marathon, you need to have a someone there behind you that has an understanding of what you are going through."

Of course, it's not just marathoners who are joiners. Many of Washington's other runners are finding it's easier to run with a pack.

There are more than forty clubs in the area for runners of all levels. Most larger clubs have an annual fee that covers the cost of training sessions, newsletters and social events. The newsletters provide information about races and other events, and often give medical tips about safe training. Most clubs also sponsor their own weekend runs and club races.

But for most runners, the clubs' greatest attraction is the camaraderie.

"I wanted to find a group of people to run with who weren't six-milers," says Mary Pagot, a runner who began by walking around the block to get into shape after her first child was born.

"I didn't want the pressure of not being able to keep up. But once I joined a club, that wasn't the case at all. There are always going to be people who run a little faster, those who run a little slower and those who run about the same."

If you're thinking of joining a club, remember that picking one is a lot like selecting the right pair of running shoes: Fit is important. There are clubs that train seriously and clubs that don't. There are clubs that are competitive and clubs that aren't. There are clubs that specialize in race walking and clubs that specialize in marathon training.

So, if the club fits, join it. ON THE RUN

To give you a head start in your search, here's a sampling of the larger organized running clubs, particularly ones that are actively seeking members.

ANNAPOLIS STRIDERS -- 800 members. An active club. Average age of members is 36. Offers monthly meetings, bi-monthly newsletter, training clinics, speed workouts, weekend runs, a running hotline and marathon training. Sponsors ten races each year. Conducts the Governor's Bay Bridge Run in April and the Annapolis Ten-Miler. Open to all. Fees: $12 for a family, $8 for an individual, $4 for students. 301/268-1165.

BALTIMORE ROAD RUNNERS -- 2,000 members. One of the largest clubs in the area. Offers monthly meetings, quarterly newsletters, running clinics, a weekly "race for pace" program and a 24-hour running information hotline. Sponsors more than 60 races each year and six to eight major races, including the Constellation Run starting and finishing at Baltimore's Inner Harbor. Conducts the Maryland Marathon. Open to all. Fees: $15 for family, $8 for individual, $5 for students. 301/882-0438.

BELTWAY STRIDERS -- 30 members. A less competitive group that gets together to run mostly for fun. Offers monthly meetings, newsletters, weekend breakfast runs and an annual club party. Open to all. Fees: $15 for family, $10 for individual. 920-1684.

D.C. ROAD RUNNERS -- 1,100 members. One of the oldest running clubs in the area, celebrating its 25th anniversary with the Hugh Jascourt Anniversary Run on June 8. Offers periodic meetings, bi-monthly newsletters, a running hotline and low fees for weekly races. Sponsors weekly races. Conducts several major races each year, including the George Washington Birthday Marathon in February. Open to all. Fees: $15 for family, $10 for individual. 474-7177.

HOWARD COUNTY STRIDERS -- 450 members. An active club with something for runners at every level. Offers monthly meetings, quarterly newsletters, fun runs and an active Junior Striders Program. Sponsors weekly races and four major races, including the Metric Marathon in November. Open to all. Fees: $10 for family, $6 for individual and $2 for students. 301/964-1998.

MONTGOMERY ROAD RUNNERS -- 1,200 members. A competitive club for everyone even if you begin by walking. Offers bi-monthly meetings, newsletters, weekly track sessions, marathon training and a "place for your pace" program. Sponsors two races per month. Conducts the Fritzbe's 10K Funfest on April 20 and Rockville's Super Run on April 27. Open to all. $10 fee. 949-9227.

NATIONAL CAPITAL TRACK CLUB -- 70 members. A close-knit club that enjoys training together. Offers periodic meetings, newsletters and weekend runs at the Washington Sailing Marina. Assists larger clubs with races. Open to all, but it helps to have a friend in the club. $5 fee. 840-9343.

NORTHERN VIRGINIA RUNNING CLUB -- 50 members. A club of serious runners with a competitive emphasis. 40 percent of its members are triathletes. Offers periodic meetings, newsletters, weekly training sessions, triathlon training and coaching. Sponsors the St. Stephen's Homecoming Race. Open to all serious runners. $10 fee. 522-1498.

OAKTON RUNNING CLUB -- 50 members. A spirited club in the Oakton area. Offers meetings, quarterly newsletters, weekend runs and periodic fun runs. Several marathon runners belong. Open to all. Fees: $15 for family, $5 for individual. 378-8991 or 938-1729.

POTOMAC VALLEY SENIORS -- 400 members. A club that started for older runners with an interest in masters competition. Offers monthly meetings, newsletters, developmental track meets and training in distance, track and race walking. Sponsors several races per year and assists in major races in the area. Open to all. $10 fee. 790-8221.

PRINCE GEORGE'S RUNNING CLUB -- 130 members. A club that combines competition with social activities. Offers monthly meetings, newsletters, speed workouts and weekend runs along the C&O Canal. Sponsors monthly club races. Open to all. Fees: $10 for family, $7.50 for individuals. 948-3749.

RACE WALKERS CLUB -- 40 members. A section of the Potomac Valley Seniors specializing in race walking. Offers monthly meetings, indoor training and weekly workouts for fitness walkers and competitive race walkers. Open to all. $5 fee per month. 941-4317.

ROCK CREEK RUNNING CLUB -- 100 members. A competitive club that also sponsors several social events. Offers meetings, newsletters, weekend runs along the canal and weekly speed workouts. Conducts several local races each year. Open to all. $20 fee includes a team singlet. 356-1273.

RESTON RUNNING CLUB -- 225 members. A club that specializes in developing individual running ability through organized training opportunities. Offers quarterly meetings, quarterly newsletter, two runs of varying distance each weekend and special training sessions each year. Sponsors one race each month. Assists in several major races, including this weekend's Nike Cherry Blossom. Open to all. Fees: $12 for family, $7 for individual. 437-5199.

WASHINGTON RUNHERS UNLIMITED -- 150 members. An all-women running club. The RunHers emphasize health and safe training. Offers monthly meetings with speakers, bi-monthly newsletter, training runs, track workouts, coaching and an annual banquet. Sponsors the Bonne Bell 10K on May 18. Open to all female runners. $15 fee. 354-4835.

WASHINGTON RUNNING CLUB -- 200 members. The most competitive club in the area. Six members qualified for the 1984 Olympic Trials. Offers monthly meetings, newsletters, coaching, track workouts, group training runs and long weekend runs. Sponsors three major races each year: the Thanksgiving Run, the Georgetown 10K and the Hecht's Ten-Miler in June. Open to all. $15 fee. 455-0575.

WESTMINSTER ROAD RUNNERS -- 160 members. A low-key Carroll County club. Offers periodic meetings, newsletters and a series of summer training races. Sponsors several club races each month. Conducts major races, including the Frostbite 5K and 15K in January. Open to all. Fees: $9 for family, $5 for individual, $3 for students. 301/876-7127.