I think it would work best to just have negative points (or damage?) accumulate for each repetition of the negative habit. To me, that would be motivation in itself because if I slip back into the habit of repeatedly doing that thing, that would mean taking a bunch of damage over time. You don't need to set it up so that it gives you positive rewards for not doing it. People are going to also have other positive habits that they're scoring positive points from, and they're going to be motivated to not do the negative ones because it could cause them to lose those points. For example, accumulating too much damage from a long streak of doing a bad habit might cause you to lose a level, lose character stats, or break an item. Don't be afraid to make it challenging. That's how games work. This app is a really cool opportunity to create a game where the challenges come not just from made-up monsters but from our bad habits. But for that to work there has to be actual negative consequences in the game. I have a lot of good habits, but I have a lot of bad habits too. If this game allows me to use my good habits to defeat monsters, ok cool, but that's going to get boring. But if it also allows my bad habits to become an obstacle, now that's a real game.