Tom Shaw wants his Gainsborough Trinity side to prove they're winners after today's FA Cup exit.
The Holy Blues were beaten 2-1 at lower level Sporting Khalsa.
"We've got to challenge our mindset and approach to football," Shaw told BBC Radio Lincolnshire.
"I don't think anybody could argue that we had significantly more athletic players, technically better.
"We looked super organised and the lads were good tactically. And we've lost.
"The spells where we can walk the ball in the net and we don't you're going to leave yourselves open to results like that."
Jake Gosling put the Northern Premier League MIdlands outfit ahead in the 59th minute before Kyle Dixon drew the Holy Blues level from the penalty spot with 15 minutes remaining.
However, four minutes later Jumaane Meggoe had the final say.
Trinity now host Morpeth Town on Tuesday.
"We've got a quick turnaround to a game on Tuesday night that could be very important for us," the head coach added.
"It's cruel how the game ends but we have to be winning the game by a good score if you look at the level of the two sides.
"We've challenged the mindset of our lads in there. Are we winners? Do we know what it takes?
"I have to put an XI out there on Tuesday that I know has got that mindset."