The scrum-half was expelled from the England squad this time last year following off-field indiscipline.
But he returned to the Red Rose during the summer tour of South Africa and has been in sensational form Harlequins.
"I am just loving life at the moment," Care told the Daily Telegraph.
"I am loving my rugby and I think I am playing some of the best rugby I have played in a while.
"Everything that has gone on in the last year has made me grow up pretty quickly. Like I say, I couldn't be happier at the moment. I am enjoying playing more of a senior role at the club, taking charge a bit more.
"At 26 I am one of the old boys around the club at the moment, which is quite scary with the 18 year-olds running around. I am obviously so grateful to Conor O'Shea [director of rugby] and all the players and staff around Quins."
While Harlequins punished Care for his off-field misdemeanours, they also put an arm around him.
And Care, who is now one of the front-runners for a scrum-half spot on the Lions our of Australia, admits he owes Quins' director of rugby Conor O'Shea a huge amount.
"Conor is like a second dad to me and second dad to a lot of the boys," added Care.
"He is always there if you want to chat to him about anything. I have some great friends here as well, Jordan [Turner-Hall], Ugo [Monye] and the boys. I think it shows a lot about the club that we stick together through thick and thin.
"I am very grateful for everything the club did in sticking by me and hopefully I am repaying them in how I am playing at the moment. There is no other club I would want to play for in the Premiership."