Not allowing clients to move on from a workout if they did not complete it on that day. Meaning a playlist view instead of a calendar view. Most people do not train on the days that the workout its assigned for human reasons, so having to go back to the day it is assigned its annoying. therefore, making a playlist view where you are doing the next workout assigned rather than having to go to the day it was assigned for and completing it. Basically a hard lock from moving forward. It could be as simple as having a button that says "Do not move on until last program/day was fininished". So if day 1 isn't done can't do day 2 yet unless athlete clicks yes skip day 1.