In World of Warcraft you must pay attention to your Mana. Being OOM is a dangerous condition because without it your character can not cast spells or heal itself. Ignore your Mana level and your health will soon suffer - death is the ultimate price you'll pay for not addressing the problem.
Over time rest will restore you, but there's no time for rest when you're on an epic quest! When that happens you must stop, sit and mana up with some special potion you've carried with you. And after a 20 second hiatus you are ready again, full of mana, to take on the monsters and bad guys of Azeroth and beyond.
It's such an important factor the game provides you with an indicator bar showing at all times the stats on your character's health and mana, and once the situation is critical a warning flashes. Time to stop and regas.
Would that we could each develop such a guage in real life. We could check on it from time to time, and it would issue a flashing warning if we dip below some critical threshold. What would your mana indicator be reading now?
And when you can't take a day or more to rest and recharge, what do you do? What helps you quickly regen when you're faced with the dreaded OOM?