Do run very gently. Do not lift your feet much. Do not come down heavily - tread like an angel. Do not run like a machine. Do not get carried away with athletic fervor. Aim for grace. Be gentle on your joints. Wear comfortable running shoes. Or run barefoot.
Do not run on two consecutive days. Do not run more than three times in any given week.
Build up your stamina with the following schedule. Most people are healthy enough to do this. If you have diabetes, high cholesterol, high blood pressure, obesity, etc., ask your physician beforehand. If you miss running for some time, do not go back and start anew - just continue along the schedule.
Alternate running with walking according to this schedule:
2 min run, 1 min walk, repeat 10 times
3 min run, 1 min walk, repeat 9 times
4 min run, 1 min walk, repeat 7 times
5 min run, 1 min walk, repeat 5 times
7 min run, 1 min walk, repeat 4 times
9 min run, 1 min walk, repeat 3 times
10 min run, 1 min walk, repeat 3 times
15 min run, 1 min walk, repeat 2 times
30 min, no walk.
Each of these levels you run at least three times - so that you need at least one week to reach the next level. Once you reach 30 min, you stay there indefinitely. If you skip time, restart where you were - you don't have to go back.
If you feel you are very much out of shape, start with 1 minute. Do not skip the two repeats on each level before you go to the next. - At all time, run with your mouth closed - breathe through your nose. If you get short of breath, run slower. - If you feel pain and discomfort in your legs, shake them out and try to run even gentler. Do not give in to a little pain. If the pain persists and gets worse, see your doctor. - Rain, etc. should not deter you - wear adequate clothing.