Here is what I have seen on the Web, note that I couldn't know your capabilities:
For completely bedridden - breathing exercises, lifting arm or leg, rest, turn, then repeat. Make fist, relax, point toes, relax. Isometric exercises: contract muscle, keep it contracted until can no more, relax.
Very weak, problem with energy production: walk until hint of tiredness, even 15 m, sit for 10-15 min, walk next same distance, rest, and so on.
Stationary bike, without load: bike as long as you can without raising pulse too much, rest, repeat.
Lifting weight, maximum you can without damage to yourself, once. Then add other muscle group.
Make some simple stretches, only make sure that your trigger points are not knotted (Trigger point therapy, see on the Internet).
Core training: balance board (standing) or ball (sitting) exercise. Don't overdo it, avoid Delayed Onset Muscle Soreness (DOMS).
Short time, good effect exercises: http://www.drmyhill.co.uk/wiki/Exercise_-_the_right_sort
Pilates or Yoga, Tai Chi, little by little.
Keep muscles and joints moving, and only then build strength and stamina, gradually.
Hope that helps.