I learned hard lesson on this wisedom. most likely you will lose if you trade what you will see, particularly day trading. the problem is: human brain is not designed to see things objectively, they see things subjectively. for example, if you feel bearish about the market, then you will take a rally pullback as a sell signal in a strong up trend, or you will see strong buy signal in a downtrend pullback.
I think the thing should be put it that way: when you trade or try to put a trade, ask yourself: " am I objective?" the most important question. you can find it whether you are objective or not: like " I want to make bla bla.. money today", " I want to recoup my last trade's loss today", " I hate this stock, so I better short it", ..... all those are subjective, if you have those things in your mind, then you will not see the market objectively, you will lose
ther question is: " do I have a strong reason about this trade: panic buy? peak sell? profit-taking ride? news is coming?...."