I have had the same problem as you, and I always have it in MMO's

You're main is a healer, so it's not exactly the same as me, cause I only want to play dps...

If you enjoy playing either tank or healer, then I would suggest playing that, cause if you're like me, you will always want to play something else, and you might as well choose the best options...

My tip is to change main job every time it's possible to do so without loosing out too much. I was maining SMN until they removed the Myth weekly cap, meaning I could quickly catch up with my DRG without falling behind.

I don't know how it will be with 2.4. If they remove Sol cap etc, I could easily change again and start over, and once again not loose anything. I will probably play Ninja in 2.4 though...

This might sound ridiculous, but it has worked for me.

I also play almost exclusively on one job at the time. So right now I always play DRG, which might sound like it would become boring, but as I get better and better on the job (could probably play blindfolded in some fights), it gets more fun actually, and I don't want to change job as badly as I did before.

It's going to be a while before 2.4 is here, so I might change main job before that, seeing as I already have maxed our my Sol gear, and can gear up another job.