Phones & tablets have the additional advantage of being able to get your attention regularly and reliably. They can train you like an animal: open this chest in

Phones & tablets have the additional advantage of being able to get your attention regularly and reliably. They can train you like an animal: open this chest in 40 minutes and that one after 2 hours. This is very useful when you're trying to create & enforce a habit (and once you're well locked into the habit spending real money for that stuff starts to seem more reasonable).