When I was younger, I had the weird habit of blowing my arms. Yeah, totally weird. I had to go to a doctor and she said I had to keep myself busy to avoid such behavior. A sport of some sort.
Mom forced me to do swimming 2 or 3 times a week. After a whole year of that, I had no desire or need to blow my arms so you can say it worked. The fact that I didn't like swimming at all back then wasn't much helpfull though.
When I think about it, I suppose swimming was the best choice since I can't blow underwater. So a sport where it's hard to pick your nose... I can't really think of any.
In case you can think on anything, that's an ideia that could work. If you want an effortless option though, I'm afraid I can't help you there.