I've had many rejections from publishers and literary agents for a book which I've put a lot of work into (https://www.wyclifsdust.com, since you asked). It's very tough, and puts a lot of pressure on one's innate self-belief. And as an academic, you probably have on average at least one rejection for every paper you write. (If you don't you aren't being ambitious enough in your journal targets!)

I like the (apocryphal) Churchill quote: "Success has been defined as the ability to go from failure to failure without losing enthusiasm."