iOS: Apps designed to help you build habits and achieve your goals are fairly common, but Balanced is one of the simplest and most flexible to use. Rather than making you feel guilty if you "break the chain", the app gently reminds you of the stuff you would like to get done.
In the free version, you can enter up to five activities you want to regularly do. Balanced helpfully suggests 50 to choose from, in categories like health, self-improvement, creativity, confidence and learning.
Once you select an activity, you choose how often you would like to do it and that's it. Balanced will order your activities based on how long ago you did them and how often you should be doing them and then notify you when it's time to act. It's pretty simple — no rigid schedules or anything, just prioritised next actions.
The paid version ($4.99) unlocks unlimited activities and features such as the ability to add a passcode, app badges, a graph view of the past month, and activity history.
Balanced (Free; $4.99 Premium) [iTunes App Store]