Don't Sit Down During Your Workout
If you're struggling to stay motivated and focused during your training sessions—because you're tired, distracted by things outside the gym, training alone with no accountability, or any other reason—try not letting yourself sit down during your workouts.
If you have to, get rid of whatever chair or bench you normally sit on between sets. Move it somewhere else in the gym outside the range of immediate convenience to minimize temptation. While you’re at it, you can leave your phone on it.
Likely you’ll pace around a bit rather than simply standing still with limp arms hanging at your side like a pervert, and this will help keep the blood moving and maintain your warmth and preparedness more.
This is a really simple but effective way to stay engaged with the workout and remain focused on what you're doing. You'll also find that you naturally take shorter rest periods between sets and stay off your damn phone more easily. It will typically make you feel more energetic as well if you’ve come into the gym fatigue and moving sluggishly.