When I first started playing on retail during vanilla, and was around level 15 on my Druid I went to my first dungeon, The Deadmines. I did not know what abilities other classes had, and simply dps'd by spamming wrath repeatedly.
About 5 minutes in, the group leader told me that I was the healer, and asked why am I not healing. I responded that I'm full health and that the rest of the group should be able to keep themselves up.:o Needless to say I have not finished the dungeon with that group.
After that incident I learned what it meant to be a healer. A friend of mine that made me buy the game also told me that healers are very valuable, and are always welcome in groups.
Therefore I leveled to 60 as Resto, most of which included a lot of painfully slow solo-grind.:( Though it paid off by doing good in some dungeon and getting invited to one of the better raiding guilds on the server without an application.
I learned on my mistake in the TBC expansion and face-rolled through the levels as feral.:D
