If there was a Duolingo for workout, what features would you want?

I've been seeing a lot of ads for "Duolingo for X" (like meditation, cooking, etc.). Some of them seem unnecessary, while others are quite appealing.

Like I haven't seen a Duolingo for workout. I think this would be a great idea - using Duolingo's gamification approach to encourage simple daily exercise.

Would you also be interested in such an app? If so, what features would you like it to have?

For example:

• Daily tasks and streaks like language learning
• Achievements, exp, level system
• Simple exercise challenges
• Different difficulty levels for the workout
• Fitness leaderboards with friends

These are just some scattered thoughts - I'm really interested in hearing everyone's opinions!