Worry is most apt to ride you ragged not when you are in action, but when the day's work is done. Your imagination can run riot then ... your mind is like a motor operating without its load.
For most of life, nothing wonderful happens. If you don't enjoy getting up and working and finishing your work and sitting down to a meal with family or friends, then the chances are you're not going to be very happy. If someone bases his happiness or unhappiness on major events like a great new job, huge amounts of money, a flawlessly happy marriage or a trip to Paris, that person isn't going to be happy much of the time. If, on the other hand, happiness depends on a good breakfast, flowers in the yard, a drink or a nap, then we are more likely to live with quite a bit of happiness.
Don't bother about genius. Don't worry about being clever. Trust to hard work, perseverance and determination. And the best motto for a long march is, "Don't grumble. Plug on!"
I went for years not finishing anything. Because, of course, when you finish something you can be judged.... I had poems which were rewritten so many times I suspect it was just a way of avoiding sending them out.