Is it true that there are ways to predict whether I will get seasick if I go on a cruise?

There is no foolproof way. Even the very sophisticated testing methods used by the National Aeronautics and Space Administration are not always reliable. Motion sickness continues to be a serious and handicapping problem in space.

However, one simple test is worth trying. Read a newspaper for about 10 minutes in a moving car. If that makes you feel ill, you may be susceptible to motion sickness. If reading does not bother you, chances are that you will not get seasick.

I am a senior citizen with a history of heart problems. Do you recommend any precautions for me for air travel?

Generally, anyone who can walk one city block and climb one flight of stairs without shortness of breath will have no difficulty with air travel. The exceptions: individuals with recent active heart and lung disease and those with unstable electrocardiograms. Obviously, consult your physician if there is any question about your condition.

And you can minimize problems by doing the following:

Get plenty of rest before and after the flight.

Do not exert yourself at airports. More heart problems occur at airports than while flying.

Drink plenty of fluids during the flight.

Take only essential medications on travel days.

Get up and move about during the flight.

I have great difficulty with my contact lenses when I fly. What can I do?

The extremely low humidity on planes removes the moisture barrier between the lens and the surface of your eyes. This causes the lens to adhere directly to the eyes and leads to irritation and discomfort.

Get eye drops for dry eyes in the pharmacy and use them every few hours. And keep the air conditioning vent, if there is one, turned off or away from your face.

I have bad eyes and am learning to ski. Will I have a problem with snow blindness?

Snow blindness is a sunburn of your retina, the inside of your eyes. "Bad eyes" have nothing to do with it. The symptoms of snow blindness are a sensation of increased brightness, irritation, difficulty blinking, redness, tearing and pain. Often these symptoms are erroneously attributed to the cold and wind. If you think that you may have snow blindness, seek medical attention. To prevent snow blindness, wear appropriate winter sunglasses. (Note that all sunglasses are not winter sunglasses.)

What is the Jet Lag Diet?

This diet, originated by Dr. Charles Ehret of Argonne National Laboratory in Illinois, claims that you can minimize the effects of jet lag by doing the following:

On the four days before a flight alternate "feast" and "fast" days. The day of the trip should be a "fast" day.

On fast days eat a few hundred calories less than you usually eat. Eat foods high in proteins.

Switch to your destination time as soon as you get on the plane. Eat meals on the plane as closely as possible to your destination schedule.

The diet is somewhat complicated -- and has never been tested by independent investigators.

You can get a free wallet-sized copy of the diet by writing: Dr. Charles Ehret, Office of Public Affairs, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, Ill. 60439. Dr. Karl Neumann is a pediatrician in Forest Hills, N.Y., who writes about travel and health.