When im down even though its terrible difficult i try to at least move that always seems to help a little. Exercise can be just doing short laps around the house so you know you dont have to go full blown exercise just keep moving, i find uo beat music helps to, avoid anything remotely emotional, that will make things worse. Watch something funny. My point being do anything you can and make sure its all positive. Its hard to do but sometimes you gotta fake it till ya make it.