The Wales flanker is only four matches into his comeback having spent six months recovering from surgery on a dislocated and broken ankle sustained on provincial duty for Newport Gwent Dragons in September.
"It feels like the start of my season. I feel really fresh at the moment and am eager to get going," he said. "I have to thank the selectors for choosing me even though I've been out for a while. Now it's up to me to repay their faith, work hard and prove my worth."
Most players would have seen their hopes of making the Lions tour vanish as a result of such a setback, but Warren Gatland and his coaching lieutenants viewed Lydiate as too influential to overlook.
The 25-year-old's outstanding defence and workrate were critical to Wales' 2012 Grand Slam - he was later named player of the tournament - and their passage into the World Cup semi-finals a year earlier.
England captain Chris Robshaw was the biggest name to be omitted from the five-strong contingent of flankers and now that Lydiate has made it, he is eager to make up for lost time.
"I've been playing for the last month, trying to get my match fitness and form together," he added. "It's been quite frustrating, but I had a better match in my last game and started to feel a bit more like my old self. The sharpness doesn't come overnight - after six months out of the game there is rustiness and timing tackles is a bit off."
Lydiate, who won the last of his 27 caps during the 2012 tour to Australia, listened to the squad announcement while surrounded by his Dragons team-mates.
"I was shocked by the call-up. I didn't expect it because I've missed so much of the season, so I was over the moon," he said. "I was in training when I heard the news. We'd just finished a session and were travelling between venues. The boys had it on in the car."
He added: "We had another session to do so I couldn't go and celebrate, but I had a lot of texts from family and friends."
- Sports & Recreation
- Newport Gwent Dragons
- Warren Gatland