I think that part of the problem is that not only have we been pushed toward the idea that we can feel fulfilled by doing certain things, but also toward the idea that we should seek this fulfilment.

I agree. I think that we are, as a species, a flawed design.

• We are supposed to be able to venerate and be faithful to a god, which we all know is not possible (to fulfill those expectations/commandments)
• We are supposed to find a partner (preferibly of the opposite sex), marry her/him and have children, and be happy in the process. We all know how difficult, if not impossible that is (either the partner part or the children part, sometimes both).
• We are supposed to associate, socialize, live harmoniously. We all know that one, of all, is impossible. Even if we don't declare war to other groups, we find ways to enter into never-ending conflicts.
  In short, it seems to me that there are tons of things we cannot do, but we insist on doing them and at certain levels. That's like asking your dog to do the shopping and prepare your food.