Create Challenge with my own saved workouts

Why are challenges only possible for a few select single exercises and god workouts? I’m not interested in challenges with those.

Please allow selecting any single exercise and also user-saved own workouts!

I think that the app should let users upload jpg o pictures from the camera roll to add them among the created workouts. So that you can have really everything in one app. Cause you can you both •the app• and •a personal trainer who makes written schedules•