"Teams of good guys, they never win," he said in Amazon's behind the scenes documentary All or Nothing.
But the manner of their win against Sean Dyche's side suggested that Mourinho's team are now made of sterner stuff.
"This is the kind of match with all the ingredients to lose two points and sometimes three. We prepared ... well but it is the game that without character and determination you lose points here so I am very happy," he said after Son's 76th minute header settled a dour encounter.
"I said before the game this was not the game for beautiful football or the game to score many goals. Sean Dyche knows how to organise a team and to stop the better teams from playing through it.
"I want the team to go to every match to win it, home away Premier League, Europa League, you can lose or draw but go to win it. This is something special, a change of mentality, of philosophy," he added.
After giving up a three-goal lead to draw 3-3 with West Ham in their last game, Mourinho felt there was a real strength in his team's mental approach.
"I have the feeling again that after we felt the pain, got the points in a positive way that tonight it is not going to happen and we are not going to concede. If we are not going to score lots of goals we cannot concede and everyone fought for that."
Burnley v Tottenham ratings
Mourinho's approach of asking Kane to play in a deeper role, often operating just behind Son and Lucas Moura, has produced the most potent attack in the league with 16 goals in six games.
"It is great, we need everyone to be scoring and assisting at the top end of the pitch. Me and Sonny have had a nice little partnership going recently and hopefully it continues," said Kane.
"Even today it was not an amazing assist but it fell well for Sonny and 1-0 away to Burnley is a fantastic result," he added.
Kane said the win, at a venue where they failed to win in the past two seasons, was a sign of real progress for Tottenham.
"It was a massive game today, it is not an easy place to come. It is going to be a tough game, a big battle and these are the games you need three points if you are going to be up there at the end of the season. Massive fight from the lads," he said.