In my experience, choosing a career doesn't always happen at the age of 18, or 21, or 30 - it's something you create as you go, guided by what your goals are. When I was 21, I wanted to meet lots of people and work on exciting, big projects, so I took a job at a PR agency with big clients and lots of fancy events and parties, but the hours were very long and challenging. Now, I am saving for a house, so I wanted a job that offered better financial benefits.
The best advice I can offer, is think about what your strengths are and what makes you happy - helping people, learning, building with your hands, staying active, or anything else - and find a job that lets you do those things.
Best of luck!
Be open to any opportunity that comes your way, listening to what others have to offer before making a decision. I'm not saying you need to take every opportunity, but it's usually worth hearing what others have to say to make an informed decision about where you want to spend your time.
Hope this helps!