A very good post from a blog of Professor Waqar Ahmed.
When I was doing my PhD I got frustrated with lack of progress so many times. Several times I quit only to be persuaded by my mum or dad, my supervisor Professor Michael Hitchman and my friends to carry on and finish what I had started. I believed that I had too many challenges, too many difficulties and not enough talent. Now I am so glad that I listened to them more than my own self doubts and worry.
As a supervisor I have come across a number of students over the years who felt the same way. They were filled with self doubt and worry. I think most students at some point during their PhD studies have at times felt the same way.
Next time you find yourself doubting yourself or worrying too much then watch this video.