I need a positive word to describe a person who usually sets a lot of rules for himself and also for others and always adheres to his rigid principles. For example, a man who is always punctual, keeps promises, avoids what he thinks they are hamful to his health, so on.
A stickler is a person who insists on behaving a certain way (usually adherent to a fixed principle or set of principles).
A person who insists on a certain quality or type of behaviour.
‘he's a stickler for accuracy’
‘I'm a stickler when it comes to timekeeping’
So you can say (for example): "He's a stickler for punctuality." and so on.