He spoke to Off The Ball's Dave McIntyre on Wednesday afternoon
Billy Vunipola admits he never let his head drop during his injury layoff and says his main goal was to come back stronger than before.
The 24-year-old underwent surgery in December to repair knee ligament damage suffered last Autumn.
"For me to get injured in the time that I did was obviously very frustrating," he told Off The Ball's Dave McIntyre.
"I was frustrated at the time but then I thought there are so many people that are worse off than I am. I always thought in my head that God always had a plan for me."
He added: "Why complain? I fully embraced it. It could have been a completely different year to what I've just done but I'm in the position I'm in now and I'm doing OK."
Vunipola returned last month for English Premiership side Saracens and was part of the team that beat Munster in the Champions Cup semi-final at the Aviva Stadium last month.
"I'm back and refreshed at the business end of the year. Somehow I've managed to sneak into the Lions as well, so I've got that to look forward to.
"The only thing I had to do was work hard. Work hard and get back fitter than I did before and be fine. That was the only thing I had to do right."
Ahead of the upcoming Lion's Tour of New Zealand this summer, he said: "Everyone has to come to the table, it's like a melting pot. You have to be as open and honest as you can be. If we're not, we're not putting ourselves in the best position.
"If we hold things back, it'll show. We have to show belief that we can do this and show positivity."