But I have no problems. On one side this is good, but on the other side, this means I have no motivation :/
I was like that too.. I really think the key is finding something you enjoy. When I was younger, since I was thin and moved around a lot bartending, I was really unmotivated... especially since I thought I should be doing cardio, which I really despise. Now I like lifting heavy things so much and feeling myself get stronger that I really regret it when I miss gym days.
The good thing about starting when you are in good health is you can make more gradual changes. Drop a meal a week that is unhealthy for a healthier one, drink an extra glass of water a day.
I totally understand it's hard to get motivated when you feel like you are in perfect health, but I have tons more energy than I ever did, I sleep better, I can carry 100lbs of groceries 2 miles home from the store and not be winded, etc.. in retrospect, it would have been nice to have more years of that.