And most of all I hated those workouts.
Then I got a weight set and started doing squats, deadlifts, rows etc. Starting Strength like routine. Was increasing weight constantly. I was in horrible shape so the workouts felt very intense at 50-90 lbs. There was noticeable muscle growth and I felt a lot more strength in daily activities.
I liked those workouts and had zero motivational problems. No mental tricks necessary, except maybe having the weights at home staring at me. The results were more obvious. Tried my old high rep routines and could do 35 25lb curls etc. Maybe I am cut out to be like Arnold, it feels like smooth sailing.
For me the case is the opposite. I get sick of feeling "burn" from high rep routines and would rather do squats then cleans that leave me panting on the floor, without burn.
It may be a genetic difference. People have different proportions of fast and slow twitch muscle and excel at different sports.
And the P90X style workouts with bodyweight do cause some muscle growth. That's how people post ripped pics of themselves after programs like P90X. A bit of muscle growth usually combined with fat loss.
I was surprised that a mere 100 lb weight set would feel so heavy even though I could do 50 pushups, 12 pullups, etc. I expected I'd need 2-300 lbs to really feel the weight, really overestimating the shape I was in after doing bodyweight drills.