I apologise to people when I need to.
I have achieved a lot and I'm grateful for that - I'm just a bit greedy because I want to add the Olympics. It's once every four years - everyone wants it and very few people get it.
It's important that athletes can compete on a level playing field. And youngsters coming into the sport can know that if they are working hard and training hard, they'll see a true reflection of where they stand and what they can achieve worldwide and not be swayed by people who are cheating.
Plenty of people who are 38 have run really well in the marathon.