Despite a stunning start to the campaign that put them in pole position for promotion, the Jags have slipped five points behind rivals Morton in the standings after a winter blip.
They have only won twice since thrashing Dunfermline in November and boss McNamara insists belief will be key as the championship race intensifies.
He said: "A lot of them are not very young, but they are only around the 20, 21, 22 mark and they are inexperienced. We try to take the pressure away from them and take it game by game.
"It is not about looking beyond Dumbarton to Falkirk or beyond Falkirk to Cowdenbeath. Every game is vital.
"We have to get back to doing things properly and not getting caught up in the hype.
"The players have to do it for themselves. Instead of looking around, they need to be confident.
"The only thing that is stopping them winning matches is themselves and I said that to them after the Dumbarton game. It is about desire and application.
"They have all got the ability and with the squad we have got, although we have got injuries and suspensions, it is still good enough to go and win matches."
Thistle's flying start to the campaign had scouts flocking to Firhill to see McNamara's free-flowing side in action.
He said: "I have had a few calls but nothing concrete. They will only attract speculation by doing it on the park, not by what they have done two, three, four, five games ago.
"Every week you need that consistency and drive. It is not what you have done in the past, it is the now.
"It is a learning curve for the younger ones, but if they want to play in a higher league that is what they need to do.
"They need to handle pressure and handle games where you are big favourites to win and you need to be dogged and match them just to win."