First off, let me preface by saying that I have a physical disability. (moderate Cerebral Palsy) I only bring this up because it plays a factor with this particular topic.

Anyway, I'm wondering how I can increase my energy levels and stamina given that I can't really do a typical workout routine. I ask this, because in my quest to become a better version of myself I've realized that these hot summer months have taken their toll on my energy. Lately, by mid afternoon I feel gassed and feel as if I need a nap. Often times, I'll wake up from a nap and feel more tired than before. I haven't done a lot of strenuous activity in quite a while and I think that it's obvious that it plays a factor. Is my best bet just to tough it out with more walking and some light lifting in order to increase my stamina? What can I do in the mean time?