What If vs. What When

"What if" can be anything. What if an earthquake strikes the Texas panhandle? What if a user forgets his password, then forgets what email he used at registration, then forgets his own name? What then?

The problem with what if is that it kills progress. What if is a laundry list of excuses for not pressing on and making things happen. What if is the secret nuke for people who like to sit and be crusty.

"What when" plans for the inevitable. What when a user forgets a password? What when I lock my keys inside the car. These things are going to occur, so go ahead and plan for them.