This to me is a bit of a funny question because I realise that a batsman can get the "red mist" after hitting a good shot or two - and we all have been there, it is just if you are going to get a big score - 50 or a hundred, unless you are Graeme Thorpe in batting in Pakistan, you are likely to need to 5 or 6 fours in a 50 and 12+ in a hundred.
I think you need to change your mindset from thinking "yes I have hit a four" to that was a nice shot, great how many more do we need to win, what is the run rate, where are the easy singles. I think my point is that largely you should expect to hit boundaries as part of you innings and you shouldn't think that just because you have hit a lovely cover drive, or moo over cow corner that your job is done.
Then, as others have said, clear your mind and totally focus on the ball for the next delivery.