Here is the single highest-value habit in all of trading, learnable today, before you ever place a trade: decide your exit-if-wrong before your entry. Not after the position hurts. Not "I'll see how it goes." Before. Everything else in risk management is arithmetic wrapped around that one act of honesty.
Why before?
Because the version of you that exists before the trade is the only rational one available. Once money is on the line, a documented parade of biases arrives — loss aversion, hope, sunk-cost thinking — all lobbying for "give it a little more room." Deciding the exit in advance (and enforcing it with a stop order — the plumbing from Lesson 4) means the calm you makes the decision and the emotional you merely watches it execute. Every legendary trader this site profiles, from Jesse Livermore to the Turtles, either lived by pre-decided exits or was ruined in the episodes when they didn't. Both kinds of evidence are instructive.
The 1% idea
So how much should a trade be allowed to cost? The classic beginner anchor: no single trade may lose more than 1% of your account. Note carefully what that means — not "invest 1%," but "size the position so that if your pre-decided exit is hit, the damage is 1%." With a $5,000 account, that's $50 of planned risk per trade. If your exit sits 5% below your entry, you can buy $1,000 worth. The formula falls out by itself: position size = (account × 1%) ÷ distance to your exit.
The math that makes it non-negotiable
Losses don't heal symmetrically. Lose 10% and you need about 11% to get back to even. Lose 33% — you need 50%. Lose half — you need a double. (Check any of these with a calculator; it's one division.) Now compare two beginners on a ten-trade losing streak, which — as the next lesson shows — is a matter of when, not if. The 1%-rule trader is down about 10%: annoyed, intact, still learning. The "it'll come back" trader risking 10% a trade is down roughly 65%: they now need a 186% gain just to visit even again. Identical markets, identical bad luck — the only difference was decided before the first entry.
That's why risk is the first skill, not a chapter at the back: it's the one that guarantees you're still present when the other skills mature.
Check yourself: your account is $10,000, your rule is 1%, and your planned exit is 4% below your entry. How large is the position?
Planned risk = $100. Exit distance = 4%. Position = $100 ÷ 0.04 = $2,500. Notice the machinery: the more room the trade needs, the smaller the position gets — automatically. That inverse link is the entire secret of surviving while you learn.