Why not live life by experience points?
From their dice-and-paper roots to the modern user-generated worlds, role-playing games have always had to deal with the question of how a character develops.  This is normally handled through experience points (XP).  Kill a were-turtle, get 5 XP.  Accrue 500 XP and you gain a level.  Et cetera.
While certainly an attempt to recreate in some way a person's actual skill advancement in real life, it would seem that XP would work in the actual world similarly to the way it does in the digital.  For example.  Let's take a skill you want to develop, say running.  Set a series of levels in front of you, and choose XP amounts for given tasks:
Go for a 1 mile run, get 1 XP.  Go for a 3 mile run, get 4 XP.  Run in a charity event, 15 XP.   Finish within 1 minute of the leader in a competitive run, 200 XP.  Run a marathon, 10,000 XP.    
Level 1: 30 XP.  Level 2: 500 XP.  Level 3: 3500 XP.  Level 4: 5000 XP.   Etc.
So, you could get to high levels just by running a mile at a time, but getting there would take forever.  Doing bigger things yields bigger numbers, and thus faster level-ups.
Here's a wrinkle:  in games, a higher level means better stats.  A level 2 character is stronger than a level 1, and that means an easier time killing beasties.  Aside from the fact that you would actually improve, how would this work in real life?  I say you'd have to have your friends involved, and the bragging rights would do it.  Either that or have specific level tasks, e.g. you can't get to level 4 until you run the Turkey Trot, no matter how many XP you've got.
This could work for all kinds of things.
- Career -- go to a seminar, 10XP. Get the corner office, 5000XP.
 - Arts -- participate in Nanowrimo, 150XP. Get published in a magazine, 500XP.
 - Education -- go to a class, 1XP. Get a PhD, 10,000XP.
 - Fandom -- read the Lord of the Rings again, 5XP.  Go to Marquette and lie about doing a research project to get the Special Collections guy to bring out the secret not-for-display Tolkien stuff, 10,000XP.
 - Connoisseur -- try a new beer, 5XP.  Go to a wine tour in another state, 1,000XP.
 - Family affairs -- email your mother, 2XP. Don't yell at Shannon on Xmas, 50,000XP.
 
If you're willing to spend hours of your life pretending to be a druid and running around killing lizards until you can get that robe you want, why not take that rewards system and move it to real life? I'll DM.
