I've never done a healer until SW:TOR, usually dps and it was initially hard to get out of that mindset
Personally, if I'm there to heal then that's what I do. Force Armor, Force Lift etc...sure but I don't go looking for the chance to toss out some DPS. I'd rather a fight take a little longer without my DPS contributing, then have a wipe because I miscalculated on resources or something.
That being said, I don't try to keep everyone at full. That's not my job. My job is to keep everyone standing. Don't ***** at me if your health drops to 50% or less, especially if your AOE broke my CC and you got reamed. Don't ***** at me because you're jumping all over the place breaking LOS. Don't make healing harder than it has to be or I won't go out of my way. Unless you're the tank, in which case I always follow your lead.