You can also pick an idea that you yourself would use ("scratching your own itch"). This removes the uncertainty of "will other people use it", and give you motivation at least until you get a demo/MVP done, to show others. It can help to start with a problem to solve, rather than an idea (that might not address a problem).
All-or-nothing thinking can lead to those dramatic swings, from excitement to uselessness. Instead of asking if it will be great or terrible, a solution is ask if the idea has some value.
Obviously, a bit of trust/optimism/faith is required. If that sounds too... religious... consider that a true scientist will do the experiment, instead of going by what he supposes. "Don't think, try". And Feynman: nature's imagination is greater than your imagination. Do the experiment, just to find out the reality. This helps to remove your ego, that can feel hurt by a failed idea... the ego protects itself by never testing the idea.
All-or-nothing thinking can lead to those dramatic swings, from excitement to uselessness. Instead of asking if it will be great or terrible, a solution is ask if the idea has some value.
Obviously, a bit of trust/optimism/faith is required. If that sounds too... religious... consider that a true scientist will do the experiment, instead of going by what he supposes. "Don't think, try". And Feynman: nature's imagination is greater than your imagination. Do the experiment, just to find out the reality. This helps to remove your ego, that can feel hurt by a failed idea... the ego protects itself by never testing the idea.