He told ESPN's Peter Gammons, in an interview that will likely be broadcast this evening:
I did take a banned substance, and for that, I am very sorry and deeply regretful.
When I arrived in Texas in 2001, I felt an enormous amount of pressure. I felt all the weight of the world on top of me to perform at a high level every day. I was young, I was stupid, I was naive. I wanted to prove to everyone that I was worth being one of the greatest players of all time.
I just feel that -- I'm sorry. I'm sorry for that time, I'm sorry to my fans. I'm sorry to my fans in Texas. It wasn't until then that I thought about substances of any kind. Since then, I've proved to myself and to everyone that I don't need any of that. It was such a loosey-goosey era, I'm guilty for a lot of things. I'm guilty of being negligent, not asking all the right questions.