Just as doing CPR in an emergency is much harder. The first time I tried to check for a pulse in a pressure situation my heart was beating so hard I couldn't distinguish the victim's pulse (my own drowned it out). Scenario practice can help. Instruct a friend to knock you over unexpected some time during a trip, and see if you keep your wits. You have to be able to forget that it is coming for it to be a really good test.

> Of course, rolling in the nice serenity of a swimming
> pool is very different then rolling out in the ocean
> or on a river.