The one I tried to add first was finger-tip push ups, but I discovered yet again that I am a weakling. This doesn't really bother me, however, it just gives me more games to play during my breaks after I do any bit of intellectual work for 25 minutes.
My new game is to do regular planks for a bit then take one hand and plant it by the finger tips and then the other and do the same and try to do a finger tip this finger-tip plank.
Let's pretend I make no progress on this, it'd still be a wonderful way to prevent me moping around during the times it is just too dang hot to go out. I will never get tired of writing about my revelation brought on by the pomodoro system -- 25 minutes of intellectual work/play and do something physical for 3-5 minutes. Right now, when a timer goes off, I choose to do a grip and core training 5 days a week (one day doing the hanging leg raises, the next the plank protocol from this post) and then I clean or tidy something.
But in reality, there is progress. It is measurable and thus it is a game. It gives a lot of hits along the way and eventually I (probably) get to enjoy a great result.