That's pretty much it. That's why you need to find a career you enjoy but also pays well, find a partner you love and are happy with and finally have hobbies. It's very important to find an outlet that makes you happy and lets you be 'you'.
To the OP:
What you're feeling is normal. Everyone faces it.
When you're young, you think, "If only my parents paid more attention to me" or "If only I had that toy" or "If only I had that cookie" then you'd be happy.
Then, you get older and think, "If only that boy/girl I liked liked me back" or "If only the school I wanted to get in to would let me in" or "If only I got that car I wanted", then you'd be happy.
Then, you get older and think, "If only my kids would listen" or "If only my spouse showed they cared more" or "If only I could get some time off work" then you'd be happy.
This desire is special - You feel hungry, there is such a thing as food. You feel lonely, there is such a thing as companionship. You feel horny, there is such a thing as sex.
This desire exists throughout your life and can be filled only by something special - You -were- made for more than a 9-5 job and a meaningless existence, and I promise you that thing exists that you're looking for. You just have to have the courage to find it, the humility to accept it and the strength to hold on to it.
gotta throw marriage and children into there but yeah that is pretty much life for most of us