"To avoid criticism, do nothing, say nothing, and be nothing." — Elbert Hubbard
Nobody wants to be a nothing. Unfortunately, you probably have attempted some sort of new activity and gotten some negative feedback from your friends and family. I certainly have. It's normal.
A little secret of mine: if you are not getting any heat, then you're probably doing something wrong. The truth is that in 90% of cases you'll get a lot of hate when doing something that people have attempted and failed. Losers/failers will try to drag you down to their level in an awful "if I can't then no one will" attitude. But you know better, my friend.
How can you tell if the critics you are getting are constructive or just hate?
Well, the way I usually go by is simple. Constructive criticism is that which helps you move forward, while Negative cricitism attempts to stagnate your progress.
Have you received some "pieces of advice" like these:
"My dad told me it's no use because I'm too old/young/fat/thin/tall/short for that."
"None of my collegues has ever attempted something like this."
"There are too many people doing this already."
If you get any of these type of feedback, consider it as just hate. Pure and simple. It's not adding anything to help you, rather it's just attacking your resolve.
If you are serious about doing whatever it is that you are wanting to do, then you have to consider all negative criticism very lightly. Flag is as hate and don't think about it anymore. You don't need that crap.
I know what you might be thinking: "what about the negative criticism that is well founded and has solid arguments?" Yes, there exists such a thing. I think I've received some of those a couple of times in my life, maybe two or three times and I'm past my 30's. Long story short: don't count on getting many of those.
It's way more productive to focus on what you need to do than to dwell on matters such as:
"Is that guy right in what he told me?"
"Will I be able to make it given my situation?"
"Will I even like it in the end?"
Like my mother always tells me: "regret doing stuff, but never not doing".
There will always be time to quit, but the time is not always ripe to start something that can be valuable. Don't be afraid to break the rules (not the Law!), as nobody did anything worthwhile by doing the exact same thing as everyone else.
So, what is it that you want to do?