By his own testimony, if things haven't gone well for Dundee United, he can beat himself up about it with the best of them.
"It used to be that, after a defeat, I'd wake up at 3am, not able to get any peace of mind," he says. "I'm getting a bit better at that aspect now, but this is still a job that never leaves you. I've got so many different responsibilities, it's unbelievable."
Go back 10 years, and few of us believed the placid, taciturn McNamara would one day be a football manager. He just seemed quiet and contemplative, the type who withdrew from any shouting match, who didn't need any of the hassle. Back then, many of us imagined McNamara disappearing off into a quiet zone someplace once his playing days were over.
"There was a time when I wasn't interested in management," he says. "When I was younger I used to see young players slagging off older pros or managers - people I respected. At the time it put me off the thought of coaching or managing.
"But then, as you get older, you see things differently. By the time I was 30, and still at Celtic, I was starting to think about it. I realised back then it's all about how you manage people. I also remember things I liked and disliked as a player, so I apply that rule when I'm dealing with my own players."
First at Partick Thistle, and now at United, McNamara is proving a determined, single-minded manager, who rejected the advice of quite a few "old heads" in the game about how he should go about his business.
"I deliberately didn't bring in an experienced guy beside me as a manager - instead I stuck with Simon [Donnelly]," he says. "We think along the same lines. Also, in terms of experience, I've been in professional football for 25 years - every day I was watching, listening, taking things in, seeing what to do, and quite often what not to do. If I'd brought in a more experienced coach, he might have resorted to the manual and said, 'look, this is how we've always done it.' I didn't want that. I wanted to do it my way, whether it works or not.
"Towards the end of my playing career I remember watching Eddie May at Falkirk, who went from taking the youths to becoming manager. At first Eddie didn't do things his way - maybe he felt a pressure to conform. Not long before he left I said to him: 'Eddie, if you're going to fail, fail doing it your way, not someone else's.'
"The key to it all is leadership. You have to be a leader, a father-figure, a social worker, everything. It has been a steep learning curve but I enjoy it. I especially love seeing my team play good football."
Many in the game doubt this sort of sentiment, especially when it comes out of the mouth of a relative novice in management terms. But McNamara is not for shifting.
"I'm quite a positive person. I went to Dundee United thinking, 'I'm going to get my team playing good football.' It was exactly the same when I first went to Thistle. I remember getting criticised by a journalist in one of my first games for Thistle, when we struggled to beat Stenhousemuir 2-1, and the guy wrote that we were trying to play 'Samba football' and that it would never get us out of the division. Well, once we got our new players in - cast-offs from here and there - and trained with them properly, we got Thistle playing some nice football and went on a few winning runs.
"It's the type of football I want to watch. Ultimately, what will keep me in a job is my team getting three points each week - but it has to be the right way."
In players like Ryan Gauld, Gary Mackay-Steven, John Souttar and Stuart Armstrong, McNamara knows he has inherited a golden generation of young stars. He says it was a key motivation for him to move to Tannadice in the first place.
"When I was at Thistle I said to a close friend that there were only three clubs I'd have left Thistle for: Celtic, Hibs, or United. I knew what Dundee United had in terms of the youths, because I'd watched a lot of their under-20s games.
"I think the previous manager at United [Peter Houston] wasn't sure if some of these young guys were good enough but, for me, youth was always going to be the way forward."
There is evidence within Tannadice that McNamara knows exactly what he is about. Earlier this season he had a minor rumpus with John Rankin, one of his senior players, who had ripped off his shirt and thrown it in disgust at being substituted. There was potential tension between the two. "I just let it go until the Monday, and then John and I had a wee chat. I said to him, 'what would you do if you were me?' He said, 'I wouldn't play for you again.' I said, 'John, we're having an argument, that's all. Have you never had an argument with your wife? We'll fix it.' Since then he has been terrific for us.
With a Scottish Cup quarter-final this weekend and 10 matches still to go in the SPFL Premiership, how high does he feel he can take United this season? "In the league I still think it's about us getting street-wise and becoming as consistent as we possibly can. I believe finishing second is still there for us.
"For me, Aberdeen are favourites for the Scottish Cup, simply because of the experience they've got. In my team I've got Rado Cierzniak, 30, John Rankin, 30 and Paul Paton, 26. The rest are all youngsters."
This likeable and determined manager chose to leave me with some self-assured words.
"No-one can guarantee results. All I can guarantee is that Dundee United will become a far better place compared to when I first arrived."