How do you know you're really in the right career?

There are lots of reasons why we stick with a particular job or career path, e.g. financial rewards, level of challenge, quality of boss, benefits, work/life balance etc. Overall the decision to stick with a particular job / career path comes down to whether, on balance, you are getting what you feel you need overall. A typical choice folk can find themselves making is that between a high paid job that gives 'enough satisfaction' versus a lower paid job that you really want to do. As we get older and commitments (home, children, etc.) increase, we are increasingly under pressure to take the higher paid job with less satisfaction. It's not all bad though as you can always 'set out your stall' and get more out of a job - carve out your own little 'niche' and get greater satisfaction overall.

To answer your question more specifically, I believe it's all about passion. And as you're 'early in life' (as you put it) you're freer to choose a career path you are passionate about.

There was an interesting study done some time ago (I can't remember who/where/when - I'd have to look it up) where a group of college graduates were asked whether they were going to 'chase the money' or pursue a career choice they were passionate about. Years later when the same group was surveyed, all of the millionaires - bar one - came from the group that had followed a career path they had passion in!

I hope this helps.