Well, I look at history and my ancestors, and am grateful that merely 2/3rds of my life is not "part of my purpose". Plus I don't actually hate work, even if it's not what I would be doing of my own accord, nor would I say it's entirely bereft of purpose. It feeds my family, fairly well all things considered, and I work in a part of the industry that is about protecting people and defending them, rather than abusing them psychologically, and that's not something I could do as effectively if I just stomped off and did my own thing. Overall I consider it a fairly good trade for what I get.

My great-great-grandparents that I know about were all farmers, using 19th century technology. I'm pretty sure they'd just laugh at the "purpose" you're talking about. Pull the other one, it's got bells on. Now shut up and go milk the cows, ye useless git.

(shudder I'd be so useless in that environment. Not just because I've been raised in my own environment, but because I know what it's like to have celiac in that environment; my grandmother did, and it was not enjoyable.)

Edit: I want to add, I'm not just showboating here for virtue points (which I detest). There are times when I'm a bit down, and remembering these things really does help me. I really do think about them spontaneously sometimes. Gratefulness is something that can take a bit of training, and I say that from the perspective of one who still feels he could stand to be quite a bit better at it, not as one who (believes he) has already accomplished it fully.