Williams returned from suspension last Friday but could not prevent his Blues side from going down to their first Super 12 defeat against the Hurricanes.
The 24-year-old admitted his enforced break, after he was found guilty of rucking the head of All Blacks and Crusaders star Richie McCaw, had given him plenty of time to reflect.
"I feel like I have had my fair share, if not more, of setbacks," he told The Sunday Star-Times.
"But when you look back I have had a few breaks as well. I was lucky at the start of my career with people leaving, so I have to take the good with the bad and promise to myself that no more is going to happen."
He added: "I have changed a lot mentally because of it. I can only control what I can control.
"It was my foot that made the mistake out there and no one else's. I could blame the citing commissioner, I could blame the rules and everything like that. But at the end of the day it was me that copped the penalty and I have to take it and stay in shape."
Now Williams is keen to join Chris Jack in the All Blacks second row for the three Tests against the Lions.
"It's an opportunity of a lifetime to get out and play them. If it happens it happens. If it doesn't I only have myself to blame.
"The rest made me really appreciate what I have got. I have learnt the hard way a lot of the times but this is such a big part of my life now and I have to appreciate it because it could change pretty quickly."