There are two kinds of discontent:
The first is one in which I am called to use the gifts God gave me to make a bigger, fuller experience of life for myself (and often what makes that life bigger and fuller is using those gifts to be of service to others). This is what Emmet Fox describes as the "Divine Discontent." It is the spark -- the itch -- which drives a caterpillar to spin a cocoon and transform themselves, even though at the beginning of that process there is no way a caterpillar on the leaf could imagine a life in the sky.
The other discontent is the ever-hungry need for more -- the part of my alcoholism which is never (ever) satisfied with what I have, where I am -- who I am -- and looks ever forward, like a cheating sweetheart slow dancing with you, but always looking over your shoulder at who's walking in the room. That part of me, made acute and intense by my alcoholism, is sure that what I have and who I am is not enough... but promises that the Next Big Exciting Thing will fix me.
The first kind can be a catalyst for great and intensely rewarding lives, and seems to be a healthy part of the growing process, as right as the turning of the seasons.
The second kind is a mofo, and it will turn you out.