It is normally that, if the healer has nothing else to do, because the party doesn't take any damage right that moment or anytime soon, you should be doing any kind of skills that deal damage, till the moment you're having to heal again. (this isn't a rare thing, even tho lots of people want to tell you that it never happens)
But here is were the fun part comes in, with today's community that's not good enough anymore, you're supposed to tank,dps, make coffee, bake a cake, take the dog for a walk, visit your grandmother, laundry, grocery shopping and clean your whole house while keeping everybody alive. If you miss one of these, well be happy because you'll be re running that dungeon since player A and B already initiated a vote kick. (this on the other hand is rare because nobody ain't got time for that, and that's when the players ingame and on the forums start complaining that a healer refused to dps or do their job)
Welcome back to FFXIV my friend
