The 44 players selected by Sir Clive Woodward met for the first time on Monday in Cardiff for a two-day get-together.
The session included motivational talks, team-building exercises and videos of the greatest moments in Lions history and British sport, with the emphasis on bringing the four nations together as one squad and building the best-prepared team in Lions history.
Woodward revealed he was happy with what he had seen from his squad so far.
He said: "This is the day it has all become real. I am determined we leave no stone unturned in our preparations and this is the first opportunity for me to sit down with the players to discuss that.
"I am very impressed by them. They are totally up for it, focused and committed to doing the best possible job for their clubs, countries and the Lions.
"I want this Tour to be different from any other with each player enjoying the experience, acting as an ambassador for their country as well as focusing on winning."