In my forties I've taken to commuting by bike to work about two times a week. Besides getting much-needed exercise, I savor the opportunity for observation and reflection. During the coldest winter months, I trade in cycling outdoors for occasionally spinning on a stationary bike. Spring put me back on the bike trail.

I cycled from the season of humming cicadas through the season of falling leaves. I biked to work 41 times from May to late November, putting in about 1,000 miles.

That's a lot of miles -- but my legs hardly felt it. They're of a solid Germanic stock and just go round and round. The 12.5-mile trip from my rowhouse on Capitol Hill to my office building in Bethesda takes me an hour and 10 minutes one way, or about 20 minutes more than my usual routine of walking and taking the Metro.

I'm on the road before 7 a.m. -- and rush hour. Once I get to the Mall, I ride on streets past the Smithsonian museums, on the wide brown sidewalks near the national monuments, and then along the waterfront pathway behind the Kennedy Center. For the last seven miles, my route is the tree-lined Capital Crescent Trail, which runs from Georgetown to Bethesda. On that part of the route, for a full half-hour, I can let my thoughts run free.

On my way, I see police on foot stopping cars on Constitution Avenue, presumably to check for bombs. They don't stop bikes. I pass government workers taking morning jogs. Some of them are lean but others are plump like me. I silently applaud their efforts. Sometimes I see a lone great blue heron wading in the Potomac River. I admire the elegant curve of its neck.

On my way home, I pass service staff taking a break at the back of the Sequoia restaurant in Georgetown, smoking or talking on cell phones. Fit young people carry sculls down to the river. I notice how young they are and reflect on how quickly I left my youth behind.

One day I notice a homeless woman lounging on a stretch of grass by the Watergate hotel, popping the bubbles in packing material. On another day a woman curses at me as I swerve slightly when she passes. I call out, "Calm down -- it's a nice day!" It feels good to stand up to her.

It's new for me to have a rigorous exercise routine during the workweek. But at the same time, I'm no couch potato. I take a 15-mile bike ride or scramble up a mountain in Shenandoah National Park on a weekend.

I pedaled to work for the first time in May, on Washington's Bike to Work Day. My fears of not being able to figure out a safe, direct route were allayed. I simply went in the opposite direction of the stream of cyclists pedaling out of the suburbs. On that first day, I felt strain in my leg muscles at the eighth mile, but I was elated I was strong enough to pull off the distance.

After I made cycling to Bethesda a regular thing, the 100 or so people commuting in the other direction came to recognize me. Some cyclists nodded or smiled. I was one of the few souls commuting from downtown to the suburbs.

I imagine I'll pass the same people for years and never have a conversation with them.

I wonder why it took me so long to take a trial ride to work when I enjoy cycling so much. I suppose it's because I resist change. Year in and year out, I read the same kind of books, watch the same kind of movies and often make the same kind of friends.

I feel good about making this change in my life. It takes effort but pays off. Biking gives me more energy. The exercise sharpens my mind. I feel calmer in the evenings.

I ponder whether I can make other efforts that would result in other kinds of changes. I'd like to become more assertive. I don't know if I could even name the fears that keep me from speaking my mind on some matters or to some people. I'd like to lose weight and keep it off; even with riding some 50 miles a week, I haven't done that. A worthy goal for the upcoming cycling season is to take in fewer calories than I burn.

I've changed one thing about my life after years of settling for something less, and that gives me hope.