Climbing
For climbers, a truer maxim has never been spoken: it's better to have it and not need it, than to need it and not have it.
Whether you're still staring up at the gym's rock wall, or you're at the top of your game and any multi-pitch big wall is yours for the taking, find everything you need to feel secure.
Ascent or descent, be as aggressive as you want with the right gear on your rack.