The 28-year-old makes his Lions debut in Monday's Zurich Test against Argentina before jetting off to Auckland with definite ambitions of facing the All Blacks.
But even a year ago Williams would have dismissed as ridiculous any suggestion he would be involved with the Lions on the toughest of all rugby tours.
"I certainly know I am a better player now than I have ever been but it has taken a while. I had a bad patch with injuries and things were not going my way and you do start to question yourself," Williams said.
"Probably a year ago, if someone would have asked about the Lions I would have told them to go away. It is something I never contemplated, it is something I thought would never come.
"It has hit me like a ton of bricks but I am riding the wave at the moment and really enjoying it.
"I don't want to go out on this tour and become a bag holder. This is the pinnacle of my career now and I want to be involved as much as I can."