LF, I'd be careful not to let a few down days or frustrating times where profits all turn to b/e cause you to change a style that works in the long run. Trading ES is about trading levels, trend, S/R, channels. There are much better instruments for scalping, IMHO.
I asked because I've been there and it really sucks (maybe I should have clarified that's why I asked). Arm yourself with patience. Not only as Rashid mentions you're tired/stressed and trading a suboptimal time of the day, but you start trading with a "job" mentality (at least I did a bit) that you don't get paid to warm your seat and that if you're not putting on trades, you're wasting your time. This led me to a lot of overtrading as in... Nodoji has given you some very good advice regarding this.