OH! That one's quite important.
Since you'll definitely meet mummies while exploring: if you've mastered Martial Arts it's pretty obvious you can take them on in tombs. The basic rule is, even if you're a level 10, when your needs' bars/mood are low you can always miss a few hits and loose - it happened to me, and I was really scared for a second of being cursed. Always fight mummies in in high spirits. Since mummies are so slow, you can easily sleep in a tent undisturbed, even in the same room, shower-in-can yourself and eat something before you face the enemy. If your Sim is extremely lonely escape to the next room, call some local guy/girl and chat.