Here's a few ideas, probably many of them wrong for you (see #3). Certainly your mileage will vary:

* Self-knowledge is the most powerful tool there is: What suits you, what doesn't; your strengths and weaknesses; your talents and blindspots; your limits; what you need, can tolerate and can't; what you love and hate; what makes you feel safe and strong and helps you thrive, and what leaves you traumatized. If you think you already know yourself, you almost certainly don't. You never fully know but you want to learn as much as you can (and in the process you'll learn to understand other people). It's the basis of every important decision you must make: Do I choose this career? Do I trust myself to take on the responsibility of this business, with all these people's fortunes and careers depending on me? Can I commit to love and care for this person for life? Is she/he right for me? Am I ready to put an infant human's life and development in my hands (and can I handle the work/life balance and pressure)? Many people make poor decisions about these issues - How can they make good ones if they don't know the key factor, themselves?

* The only way to develop that knowledge is to try and fail, and then to get up and try again (an essential skill in itself). You can't learn these things by just thinking about them; they aren't in a book. And now is your chance. Later when you have a career, a mortgage, business partners, employees and children depending on you, you can't take a big risk to just suit yourself. Also, I'm not just talking your career, but all aspects of your life: Relationships (especially relationships!), where you live, your lifestyle, etc. People playing it safe will question and criticize you (see below), but just smile and know you are moving ahead while in ten years they'll unfortunately realize they have learned little of life and themselves.

* Learn to ignore everyone's advice and criticism and to trust your own instinct and thoughts. Nobody else really understands you or your situation nearly well enough. They might have good ideas to consider, but you know best (which requires that self-knowledge). No matter what you do, people will criticize you. Even Steve Jobs was fired, Bill Gates reviled, and Martin Luther King was hated by many and polls show he was unpopular during the civil rights struggle; you could be President of the United States and people daily will call you an abject failure. And you will fail constantly, sometimes horribly, just like the rest of us, and while you are failing there will be no promise of success. Given that you will face criticism, questions, and failure no matter what, and that there is no promise of a good outcome anyway, at least do what you love and think is best, and enjoy the ride.

* Gather some data: Look at people at the other end of life, or ask them: What turned out to be important? My guess is most will answer, their family and personal relationships. Few people wish they had spent more time at work; many wish they had spent more with family. Finally, a good marriage is perhaps the most valuable thing in life but it takes far more than love and good will; it takes dedication, hard work, skill, and, as much as anything, self-knowledge.

I hope some of that is helpful!

EDIT: A minor edit or two