When you do have some energy, just take a walk!
walking is really relaxing and good for the soul and heart! you can actually help yourself out in so many ways by just taking a 10 to 30 minute walk every time you get a chance, if you are just getting started, not need to over do it at all, just take a walk outside on a nice day and enjoy yourself, maybe find some friends or family to go and walk with you.
Maybe it is time to get a dog? Dogs LOVE to go on walks with you, and most of the time they will help you keep a good pace and not stop early because they just want to keep going!