When you are ill you can't do any exercise,
but I feel that when you are injured it is important,
as much for your confidence as your fitness, to
keep training in whatever way you can. Initially,
this will mean only performing exercises that
don't involve the injured area. For example,
with lower leg injuries it is often possible to
swim or cycle perfectly safely. Also upper body
circuits and weights are generally okay. If in
any doubt about what you can do always ask a
professional.
Finally, when you are building back to full
training make sure that you increase the intensity
slowly and don't risk any reoccurence of the
problems. The old adage of ensuring that you
can walk before you can run is not only metaphorically
true, but also literally so.
Above all, as far as your future in the sport
is concerned, getting the problem completely
sorted and yourself back to normal is the most
important thing.