To add to the last post here are some great thoughts from Seth Godin. I have copied and pasted the entire post cause I reckon its on the money
Rightsizing your passion
Excitement about goals is often diminished by our fear of failure or the drudgery of work.
If you’re short on passion, it might be because your goals are too small or the fear is too big.
Do a job for a long time and achieve what you set out to achieve, and suddenly, the dream job becomes a trudge instead. The job hasn’t changed–your dreams have.
Mostly, though, it’s about our fear. Fear is the dream killer, the silent voice that pushes us to lose our passion in a vain attempt to seek safety.
While you can work hard to dream smaller dreams, I think it’s better to embrace the fear and find bigger goals instead.