Good tracking is the best way to make it interesting. If I know I did 120kg for 7 on the bench last week, I know I need to beat it either by increasing weight or increasing reps. I remember how hard it was but I've done it, so I need to beat it. It's fulfilling in ways that I find other workouts just can't be.
In terms of intensity, this video is great for working out if you're quantifying it correctly: https://www.youtube.com/watch?v=77nX_bMe5fA