London Irish hooker Harry Allen says cage-fighting helped him through his one-year suspension for taking drugs.
Allen, who had his contract ended by Harlequins in December 2013 after testing positive for cocaine, made his return with London Irish last month.
He took up mixed martial arts during his ban to help maintain fitness.
Allen, now 23, told the Sunday Telegraph: "Ten months in, I got to the semi-pro level and fought for a title. I lost it by a split decision."
Allen said he "broke down" when he told his parents about the ban.
He added: "I won't forget the look on my dad's face when I told him. That's enough for me to not ever do anything that stupid again."
London Irish offered Allen a way back into the sport because of an injury crisis.
He played in an A League match before returning to Premiership action when he came off the bench in the defeat by Wasps on 21 December.
He made his full debut in the loss at Saracens on 3 January.
Allen said: "I can't tell you the motivation that I've got coming into this. I've had a year to work out that this is all I want to do.
"I've done the time, it's been a hard year for me, and now I've been given a great opportunity. I'm not going to let this slip."