why do we do what we do?

I am wondering today why we spend so much energy, time and effort on doing something that neither gives us satisfaction nor a stress-free life..sometimes we just go with the flow without realizing that there is a need for change. The change doesn't need to be a transformation!! Maybe change means to stop and re-think - what is my purpose? what is the meaning in what I'm doing? maybe just giving yourself a reality check!!