[onorton]

"exhausted that the rest of the night is down the drain."

If you're going to the gym after work (and after getting home) that might be the problem. Everyone I know who works out either can take an extra long lunch break and do it then or get up an extra hour/hour and a half and do it in the morning. It's usually a lot emptier in the morning as well.

Also, there are a lot of activities you can do that don't even involve getting to a gym. You could do a 15 minute jog out and a 15 minute jog back. You can also do most bodyweight exercises at home.