i find exercise gives me the energy the chocolate and fast foods used to give me and you dont feel depressed after wards there are no regretts after exercising maybe you just need to add it to your day?
I would also be taking a good multivitamin to balance out your nutrients . I think your body gets used to eating crap and when you change it goes into melt down for a while .. But its comes good and then ytou feel good again and can get exercising..
also make sure you are getting enough sleep .