Lesson-1 is Patience. Ask yourself if you have enough patience for going through playing the same things again and again and again!
Playing guitar has to be a part of your Life, exams, family affairs, health issues will be there. But You have to keep one thing in mind, If you have to eat everyday, You have to be with your guitar everyday till the end of your life!
Do not ear what others can play, Learn to play your phases. Merits differ on the learning phase, so do not bother he can play this I cannot!
Learn from a Professional Guitar Teacher, YouTube is not a school but a tool to help you.
Remember. it takes 1000 days to learn guitar, but 1 day to quit! The cost is heavy!