If there is anything in life to worry about at all, it’s your wasted yesterday. Unfortunately, before you worry about it, you have to waste today doing so. Never worry!

I'd prefer 'be strong' than 'don't worry'.

Never ever compare yourself with other people. They may have what you don’t have; you also have what they may not have. Over-watching what they have is over-looking what you have. Use what you have.

Never stop learning to be who you are meant to be just because you have found someone and decided to be like him/her.

Don’t give up. You have invested a lot of time already.

Leave complains behind; Stop worrying and murmuring about the difficulty of something that you have not even attempted doing! How do you know that it's difficult if you have not even attempted doing it? Go, give a try!