Going into this phase of underestimating myself is seriously damaging and time consuming. I totally reject doing thing I love, which makes me miserable!
To overcome this feeling I usually leave the task I'm attempting and do something else like:
-watch an inspiring film
-talk to my friends
-listen to music
-take a nap
And if all fail I usually watch cartoons with my little sister.
These days with all the pressure from school, parents, peers and the media to be successful we can all go into this phase of underestimating our own abilities. Remember everyone is different and we are all talented in our own way. Just because you're not top of the class at school doesn't mean you will fail in life. Just because you failed at something you love, keep trying and you will succeed. Last year I entered a fashion competition and everyone was telling me 'you will get through to the finals' and I tried to act modest but I really wanted to get through. Unfortunately I didn't make the finals. I was torn but got offered to work backstage at the show. I accepted because it was still an experience I didn't want to miss out on. While working at the show I was inspired to keep designing and improve my skills because one day I might get through to the competition and achieve even more in the future. So next year I will enter it again and fingers crossed I will make it.
Like the saying: if you fall down pick yourself back up!