The Lions are looking to pick up a series win over the back-to-back world champions this summer for the first time since 1971.
Seymour, who is one of three Scots to be named in Warren Gatland's side, believes that he knows exactly what is required to get the better of the Kiwis.
"We've got to be willing to go through a lot of pain to beat this side," BBC Sport quotes him as saying. "We've just got to be at our utmost. We've got to make sure we know everything we're trying to do on the field inside and out. Everything's got to be second nature.
"We've got to be willing to be physical with them; we've got to be willing to play as well. We've got to go out there with ambition - there's no point in sitting on our heels and hoping you're going to have a physical confrontation with them.
"You've got to be willing to play and expand and really take the game to them as well. So I think for us it's just about getting as much detail as possible on the field, and once we've got that detail making sure it's second nature."
Fourteen of the 41 players selected by Gatland have turned up for training in South Wales this week, with the others still needed by their club sides.