TikTok suits minutes per rep well. The feed has no natural end, so the minutes you earned become the end you set yourself.
On iPhone
Tap Pick apps in App Lock and tick TikTok in the system window. If the lock is not on yet, the setup guide has the two steps before this one.
In the same system window you can add tiktok.com under websites. Do it: without it, a search result opens TikTok in Safari and the lock never sees it.
On Android
Grant usage access and display over other apps when App Lock asks, then find TikTok in the game’s own list.
The lock on Android covers installed apps only. If you open TikTok in a browser, the lock will not stop it. If that is your habit, pick the browser too, or accept that the lock covers the app only.
What the minutes buy on TikTok
At the starting rate, 20 push-ups give 20 minutes. Squats count at half the weight of a push-up, so 20 squats give 10 minutes; a one-minute plank gives 9. The clock runs only while TikTok is on screen, so closing it after one video costs you that minute and no more.
There is no partial lock. The lock covers the whole app, so you cannot keep posting open while the feed stays shut.