"We can't win this thing if there's egos or problems in the camp," said the Liverpool striker.
Roy Hodgson's men will be looking to put previous tournaments' disappointments behind them and return from France victorious..
"It's about us being here as a team. I look at other countries in many competitions and when they score everyone is off the bench and they are all involved, all jumping on each other celebrating - and that's how we have to be.
"We have to be a team. It's very important, on and off the pitch.
"We don't have our mums, dads, kids and all those things here. So we're our family and we have to be together.
"It's not about 'I have to play' or 'he has to play'. If we're not here as a nation, and as a team together, we won't win it. That's how it is."