It takes time to pick up your life and regain your energy and feel part of things again.
Maybe in a few weeks look at an Encore program to get some fitness back.
I looked at my diet as I was carrying a lot of weight. Check out Michael Moseleys Fast800 and have a read. It's based on all the good stuff we really should be eating and the books have some great easy recipe. Weirdly focussing on my health and fitness and not my illness gave me new things to talk about with others and basically gave me something else to think about than cancer and treatment.