A friend once told me your job can offer one of three essential things-
1) Good Pay
2) Opportunity for career advancement
3) Fulfillment / Satisfaction (to include optimal socialization, or lack thereof)
If you have two of the three, you're doing very well, and should utilize your free time to gain the missing third item.
Usually, a job is a toss up between #1 and #3, but not always.