As any experienced tank or healer will tell you, sometimes it’s stressful as HELL. But I do it anyway, because what I really love is helping others. As in having the ability to keep others, especially my friends, alive.
Guild Wars 2 gets rid of tanks but still has healers, though they're nowhere near as powerful as some other games. Everyone is responsible for some amount of DPS, as well as their own safety. Luckily, there are incentives to help others, like XP for reviving downed characters, both players and NPCs. While it makes for interesting dynamics, as a healer for the better part the last six years, it's hard to break away from that role. Like GeeCee, I love keeping my friends alive.