When you don’t feel like working out - you sit your ass on a machine and listen to music.
I rarely sit down at the gym. Even if the equipment has a seat, I stand or squat or lunge.
I understand that for heavy lifting you sit for support. I get that for corrective rehab exercises you sit to focus. But besides those two reasons - you do not sit!
Try standing, squatting or lunging to do your exercises that you would normally sit. You will get more muscles working, engage more torso control and it will be a lot more challenging.
Or if you just don’t feel like working out, go sit on the the inner and outer thigh machines and listen to music while moving your legs. I literally listened to Adele while doing these exercises.