Never underestimate the effect a few tweaks to the ancient parts of your brain can have. As one anecdote, I was quite surprised how much of a difference was made in my motivation by coloring my passing/failing test cases green/red using ANSI escape sequences.

It sets goals very clearly outside of 'I need a working system'.

Zynga made vast majority of its money from the people significantly older than 14. And they swear by gamification.