I should have pursued a career in what I wanted to do rather than what I thought I should do.
Although I have been all over the world, I should have travelled more when I jad no responsibilities eg. A long overland journey by car/bike/moto, but due to work/career issues didn't feel that I could leave it all for 6 months or a year and pick up where I left off.
With hindsight these were excuses and I should have travelled, come back and started again at something different.
All in all, I have had a good life so far though.