I read a good one today..
A temporary loss of value becomes a permanent loss of capital if you sell..
That is why so many lost in 2008...They panicked and sold...So the temporary loss became permanent.
Also if you are positioned well, a 1% drop in the market only translated to a .1% drop for me..I plan more to lose less when the market goes down, than I plan to make it big when the market goes up.