Exercise can be an important part of the recovery process but just giving a general response isn't the way to go with chemo. Your friend should consult his/her doctor who will probably be able to give a list of exercises that are beneficial to recovery. The other thing the doctor will give him/her is a list of things to look out for which can be important because to much exercise or the wrong kind of exercise could set recovery back.
"The best way to know how to handle situations with somebody in a wheelchair is to ask somebody in a wheelchair." ~ Daniel Sutherland