Maintaining good posture is very important. Keep the ears, shoulders and hips in a straight line, with the head up and stomach pulled in.
It is best not to stand for long periods of time but, if you must, walk as frequently as possible and wear shoes with cushioned soles and low or no heels.
Riding and driving for a long period of time increases back stress. Move the seat as far forward as possible to avoid bending forward. The seat should be reclined not more than 30 degrees and the seat bottom tilted slightly up in front. For long rides, you should stop and walk about every hour and avoid lifting heavy objects immediately thereafter.