The only thing you can do is hit one shot at a time. I think the reason you see pros get on a hot streak is because after a couple good shots you start to feel extremely confident over any club not just the club they have been using to hit those shots (like us favoring a 7 iron since we hit it pure last shot but hit the 8 iron thin, you have to be confident with all the clubs not just the one you had success with most recently). I know after a couple consecutive good shots my mind says "this is going to be a good round" and I think that's my confidence builder that helps me under par or whatever it may be.
The only way to continue the momentum is to not let a poor shot or an easy miss get you down. A lot of us mere mortals hit a poor shot and it ruins the round. You duff it on a par three, you get upset and you finish the hole with a double bogey when if you kept your composure, you probably could have pared it.
THE ONE THING I really think about during a good round is tempo. I don't think about the next hole or the last hole or shot for that matter, it's always about what's currently happening and adapting to what you have to work with so if your tempo is good, trust your swing and fire away. The killer to any poor round I have ever had was letting the last shot get to me and make me feel uncomfortable, that just builds and builds until you implode.