You are right. You probably won't have best results until you invest objectively. This takes work and experience. Everything about investing is the opposite of what the uninitiated think it is. I know I had to revise my whole way of thinking and many others have had the same experience. Nicholas Darvas book How I Made $2,000,000 In The Stock Market is the best description of this process I have seen.Is this a fancy way of saying "let your emotions dictate your investing strategy?" I feel like this is a game that should be played as objectively as possible, not subjectively.
Another way to put it is you have to paper trade as if it was real money and trade real money as if it was paper. In other words take your practice trading seriously but don't let your emotions control your real trading. I find if I am getting too caught up in trading it is because I am trading too big. I have to scale back until the amount on each trade seems trivial, hardly worth the bother, certainly not worth worrying about. Then slowly build up from there.