Anyone can achieve anything, and people achieve most what they have passion about, This sucess is amplified the more they do that activity. If someone says you can’t achieve what you want, and do it on a regular basis I would recommend including them less in your life. Its giving you negativity, and you aren’t getting reassurance or confidence in your own abilities. The last thing you want is for someone to offer to you something you want, and you end up hesitating or turning it down because you don’t think you can, when in reality you are more capable than you realise.
I’ve known a few people who have let the discouragement get to them, they stop pursuing their dreams and ended up in a bad place in life having no aspirations, hobbies or knowing what they want to do in life, they give up on higher education or pursuing a better job.
If someone says “you will never be able to drive”, take up lessons, improve and pass your test. Flaunt your success back at them and give them a reason to believe in you more.
The only time I would say it is valid to listen to other people, is to do with Education. Take for example the classic if you want to study art, drama or music, and can’t find a job afterwards, it won’t serve you well. I would say 5% of the students and friends I have known from those classes have got a job in the related fields after. There is no reason you can’t study another subject you also enjoy with a higher future prospect and still practice your art, visit theatre, take up acting or practice an instrument as you main hobby at home. You can even get a good degree, and return to education afterwards for part time courses to study your favourite topic while still having a good job.
But some common sense should be applied, if your friends discourage you from taking meth at work its probably worth taking that to heart.