A quitter never wins-and-a winner never quits.
Opinions are the cheapest commodities on earth. Everyone has a flock of opinions ready to be wished upon anyone who will accept them. If you are influenced by "opinions" when you reach DECISIONS, you will not succeed in any undertaking.
When defeat comes, accept it as a signal that your plans are not sound, rebuild those plans, and set sail once more toward your coveted goal.