CARROT Fit is a fitness app that runs you through a high-intensity 7-minute interval workout. By this it means doing 30 seconds of an exercise at high energy, 10 second break, then a different exercise for 30 seconds and so on. It's a $5 app and it has 12 different exercises with an in-app $2 for another set of 12 different exercises.

There is a sarcastic/sadistic computer AI urging you on. It syncs with Apple Health (which I think means best on iPhone since iPad doesn't have Apple Health as far as I can tell) and you can enter weight here too. The exercises have funny names and descriptions.

I'm not sure this is the app for me. Interval exercise is for more fit people and my body is not that limber for some of these exercises (e.g. an exercise like stepping on and off a chair is quite knee-killing to me). Still I think can try to use this app more and skip exercises I can't really do (you can't enable/disable exercises though you can setup a custom, and static, workout set).