It’s hard to get used to being turned down.
Being rejected is a normal part of life as an academic. We get rejected by grants, papers, collaborators, and jobs. I have recently been turned down by two major grant applications that I spent a long time working on. More disappointingly, they don’t tend to be “move fast and break things” as is hailed as a way to learn; grant applications (and to some extent paper rejections) tend to be slow and with various amounts of helpful feedback. These two most recent grant rejections were over a period of 9-15 months each, and one has come with only limited feedback.
Some people have commented that I’ve not discussed my failures enough on here, which is a fair observation. These two grant rejections certainly fit the bill in my mind. There are of course many positive ways to spin it: I had some quite positive reviews, I got invited to interview for one, I have learnt lots, it probably increases my probability of success next time around etc. But that doesn’t take away that the outcome was not as I wanted.
I have applied for 28-29 grants or posts within the last three years:

That gives a reasonable account of the amount of applications I’ve submitted and been unsuccessful in. This doesn’t include the many that I drafted and then thought my probability of success was too low to even submit. Remember, for every single one of these I genuinely believed I would be successful.
Concurrently, I have had a whole series of paper rejections. There is one particular paper that has now been rejected TEN times, all by reasonably top-tier journal, because I continue to believe that it is a meaningful high-quality piece of work. I have made edits to substantially improve it along the way (i.e. almost completely re-write the paper) and yet I’ve had another rejection within the last week [by foolishly going back to a journal that had previously rejected an earlier version of it!].
The two previous big academic failures that stand out in my mind are when I failured paediatrics MRCPCH first time and when I applied for PhD fellowship funding first time. Both of which I was completely unprepared and arrogantly went in thinking that I could simply wing-it because I had a decent track record. Obviously these sorts of things need meticulous preparation and even then the odds of success are low.
I know that this is the game and how it goes, but that doesn’t make it any more fun when it happens to me.
Almost everyone who I know who is excellent and has got big grants/fellowships was rejected first time around. So I’m hoping that this is all part of the course.