What usually helps me to get them to use the treadmill on their own is to praise them after putting them on the treadmill. I find that anything I praise my people for, they'll do again on their own.

I also praise them for any health-improving activities, whether I have them do it or they do it on their own, and I give them the hand sanitizer and fruits after they are sick, when they are available.

Something else I do is to give them the fruit to praise them, when the fruit is available. Not only does the fruit praise them, but I've noticed that it also boosts their health, their energy, and raises their fed bars a bit.

Also, maybe try having them sit down to a meal three times a day.

I hope this helps!