Actor Robert Downey Jr. tried marijuana for the first time when he was 6-years old and it seemed to go downhill from there. Throughout his late teens and early twenties he developed serious addictions to cocaine, heroine and other drugs. Downey Jr. was arrested several times, and attended several rehab clinics, and even prison.
Downey's career as an actor subsequently suffered. It wasn't until 2002, after he was last released from rehab, that he finally cleaned up his act and magically turned into the man he is today: a renowned, Oscar-nominated actor. UPI/Jim Ruymen