This is an app that I personally use often and that might be useful for some of you as well. Habitica is a to do list, but with a twist: it's also an RPG style game.
When you set up an account with Habitica, you are able to make a little character avatar. By completing tasks on your to do list, you get in-game gold to spend on armor and weapons (or some real life rewards that you set for yourself) and your character gets stronger. Miss some to do list items and your character loses health. And your character can go on quests to fight monsters, collect pets, and get some other special items.