I'm a bit like you in that I run in the evening through the week & earlier in the day at the weekends. Sometimes I do feel more energized after running earlier in the day but just have to fit it in when i can
I vary my exercise and do morning and evening sessions. I prefer the morning because then it's done and out of the way! I also feel a lot more alert in the mornings whereas I sometimes struggle after work because I'm so tired!
Yeah, that's another thing...Sometimes if I've had a long day at work I make excuses to just run for half an hour instead of the normal hour. It seems reasonable in my head at the time, but when I get back I regret it!
I'm familiar with those excuses too and when I convince myself half an hour is ok, I still don't work as hard! I'm walking every day now and I'm enjoying it a lot more than the gym!