I'd have stuck this in the Top 5s but I can only think of 4.
Reaching the age of 40 with all my hair, teeth and important bits relatively intact
Becoming a P+B mod after only 12 years of not getting into arguments or calling anyone names
Running a marathon (although I did walk a bit of it)
Winning £10k on a quiz show (at the 10th time of asking)
Over to you.