This may contribute to your missed putts. Try to breathe slow a deep when reading your putt and when you get in your stance. Let the tension go out of your body. Focus only on the line and speed in your head, nothing else. It really does not matter if you make the putt or not. Life goes on. You Mother still loves you whether you miss the putt or make it! When you relax this way, you will get more consistent with your stroke and it will help you game overall.
I have to agree with this, just look at some PGA tour averages
% Made putts by distance for 2013,
20-25 feet: 11.67%
15-20 feet: 17.83%
10-15 feet: 29.82%
5-10 feet: 54.7%
Just to put it in different terms. Pro's just barely make 1 out of 10 putts from 20 - 25 feet.
TV has really made it seem like Pro golfers drain every putt when they don't.