Trend following strategy should be done like insurance.
Actuaries do not look at one person to get an expected value.
And you should not look at one trade.
A great trend following strategy should look at many trades, many gains and losses, and many expected values.
Understand the expected value of your trading.
Listen to Larry Hite, as quoted by Jack Schwager:
What makes this business so fabulous is that, while you may not know what will happen tomorrow, you can have a very good idea what will happen over the long run. The insurance business provides a perfect analogy. Take one sixty-year-old guy and you have absolutely no idea what the odds are that he will be alive one year later. However, if you take 100,000 sixty-year-olds, you can get an excellent estimate of how many of them will be alive one year later. We do the same thing; we let the law of large numbers work for us. In a sense, we are trading actuaries.