I've noticed that if I get home, and then wait around...
Like if I sit down, and relax, or turn on the TV, or basically take any time to really slow down...
Then it's like quick sand pulling me in, and I get even more tired.
A good trick for me is to go right away to the gym, or on a run/walk/hike/etc.
The shorter the break between work and working out the better for me.
Don't think, just DO!
Kind of like what Steve Pavlina talks about in the "Getting up without the snooze button thing." Just applied to working out instead.