Years ago I went through some neurotherapy with a local doctor [1]. One part of the process had clips on my ears and a sensor on my head to read biofeedback (or something along those lines).

The game was simple: there's a silo on the screen with a hot air balloon on the left side. When I get into 'the zone', the balloon goes up and around the silo. This will loop for as long as I can hold it.

It took about two sessions with minor success, then suddenly it clicked. Now I can easily enter that state on demand.

This might sound odd, but the neurotherapy helped eliminate a lot of the negative parts of ADHD without losing the edge that a lot of medications take away. I still have a lot of energy, but I can always sit and focus on the task at hand when I need to.

[1] http://www.swingleclinic.com/about/how-does-neurotherapy-wor...