Attack coach Sam Vesty says Saints' roller-coaster 59-33 win against Newcastle Falcons was all about mindset.
The black, green and gold endured a torrid start to the game, falling 21-0 and 28-7 behind.
But they bounced back in ruthless fashion, scoring nine tries as they set up a home Premiership Rugby Cup final against Saracens on Sunday, March 17.
And though Vesty was happy to see his side get through, he knows they can't afford to repeat the kind of sluggish start they produced against Falcons.
He said: "Who won the first 20 minutes? Newcastle, by a mile, because they wanted to run over us more than we wanted to run over them.
"Once we got ourselves off holiday (Saints had last weekend off) and went 'right, we're going to run over them', we saw we could play better rugby than they could.
"And ultimately it comes down to that mindset.
"If you don't turn up with the right mindset you're out of the game.
"All of the good stuff we do is built on the mindset and we have to deliver that first and foremost.
"It's really easy to look at one side of the scoreboard and get excited but if we turn up and play like that, we're not going to win many games of rugby.
"What I'm really chuffed about was that there was a challenge there when we were 21-0 down and we calmly went through the right processes to get back in the game.
"And when we got into our stride, we played pretty well, found space and we had Hutch (Rory Hutchinson) and Furbs (George Furbank) out there with their eyes up looking for spaces.
"The ball moved really nicely to the space and we became a real attacking threat."
Tickets for Saints' final against Saracens at Franklin's Gardens will go on sale on Thursday at 9am.