How do you get the energy to focus on tasks after work?

Between the work and the gym I’m essentially a zombie when trying to study for a test after work. It’s for an engineering license and if it weren’t for guided problem sets and solutions I’d be absolutely dead. I did it a couple years ago to graduate with my masters buying coffee after work but my sleep was shot. Have to be semi present at work to get paid so am struggling. Recently taking a natural hormone boosting supplement stack and it’s doing great but I want to really push it now. Making dinner and cleaning up/ getting ready for the next day leaves me with like 2 hours at most if I’m lucky during the week.