We can be our own worst enemies. We doubt ourselves, rethink our dreams, talk ourselves out of plans, and allow naysayers' voices centre stage in our brains.
This happens in life plans, and it happens in career plans.
But here's the thing: your life is yours to live, and if mom thinks studying whales isn't a great job, that's fine, she doesn't need to do it. If that's your passion, go for it. Maybe your Uncle Ted, who is like a second dad to you, considers sales a tough gig. That's fine, he can be an administrator. Likely mom doesn't like water (or fish!) and Uncle Tom is not an outgoing people person.
You must find a job that you love, one that uses the talents that you were born with, the skills you enjoy using, the interests that excite you, energize you, tantalize you! (This may be a revelation to some, but you don't have to "work on" fixing your faults. Check out Marcus Buckingham's books on using your strengths.)
Seek out opinions, but do weigh them. And the opinions that are offered, unasked for? Those are almost certainly weighed down with the person's own biases, according to his or her values, motivators, and 'druthers. Likely they have nothing to do with you or your reality.
I believe that everyone deserves meaningful employment, where "meaningful" is defined as having meaning to that person, not to mom or Uncle Ted.