Thank you for asking a very profound and accurate question!

In my experience, the biggest warning sign is when your own small wins start to fade away. As soon as you start feeling a strange heaviness or incompleteness in your mind by watching the 'highlight reel' of others instead of being proud of your progress, understand that you are falling into that trap.
When motivation slowly starts to turn into an 'inferiority complex', it's the right time to ask yourself, 'Am I running my own race or someone else's?'"