Well, let me explain it to myself and write it out one more time.
You should approach each trade as if you were buying a lottery ticket. You have a fixed cost for that ticket, which is your stoploss, that will get refunded if you were right.
This way you do not perceive that loss as a loss, and do not see yourself as a failure, because you feel like you paid that ticket at the moment you made the trade.
If you do it the other way around, and forget about that (potential) cost until it happens, you won't be ready to accept the loss when it happens, also because you will not have set a given loss level, and that loss may be too big to accept.
For example, on my last trade, without this analogy, I would have bought 3 contracts, but that meant a lottery ticket of 300 dollars, which right now I don't feel comfortable with. So, thanks to the analogy, I ended up buying one ticket for 100 dollars. The ticket for 300 dollars would have given me a potential jackpot of three times as much, but I didn't go for it.
Once you perceive everything in terms of risk/reward (as long as probablities are also on your side), you can afford to even make bigger bets, like investing all you got on one future, which is something everyone advises you not to do, but which makes sense if you are able to take your losses.
For example, say I am positive we just hit bottom, because of pivots and beacause of round numbers on the EUR, like 1.5 and there's a pivot line right there... say I want to bet on that. If the stoploss is just ten ticks lower, and I place it there, I could afford to buy 5 contracts, with a stoploss of just 600 dollars. Yeah, that is a lot, but if you stand to make 6000, you might want to do that.
What I mean is that, as long as you have the lottery ticket cost in mind and know exactly how much you'd be losing from a given trade, you can do anything you want. Nothing should have the power of scaring you, because you know exactly how much money you'll be losing if you are wrong, and you're accepting that.
