Follow your heart. Everyone develops at different levels, speeds, and at different times in their life. If you’re really interested and excited about planetary exploration, you should go for it, but you should also be very aware of what the limitations are of any career path that you decide on. Make sure you’ve learned as much as you can about it, before you just leap into it.
Growing up in the New York city area opened my horizons to the diversity of our society, the occupations available, and to the importance of choosing an occupation that you enjoyed. I always remember being interested in why things were the way they were. What got me interested in geology was wanting to know why there were mountains and valleys, how they got that way, and the prospect for working in the field (outside of the office)! Planetary geology was even more fun because you could study not only the Earth but the other planets as well.
Hiking and exploring the American west.