If you can't handle criticism, get out of the pool.
If you don't have the fundamentals of grammar, there is no hope for you as a writer.
How many of you have heard something like that in your writers groups?
You'll never get better if we don't tell you what you've done wrong.
There's always that one guy (and I'm sorry, but it is often a guy) in your MFA who thinks he knows exactly what your work needs, even though his manuscript about a sentient and altruistic centipede in a dystopian hellscape is just as unfinished as yours.
True story, I am days away from my 37th birthday. I published my first novel this year, and I just turned my third novel into my agent. I have not taken any kind of writing or English class from an accredited educational institution since I was in high school.
I wanted to tell you that you are writing for someone other than yourself...
That was the last English teacher I had. He wrote that late in our second term, on a journaling project that wasn't supposed to be about grades or content, but just about the act of writing. No one had ever told me they looked forward to my writing before but, 20 years later, I still remember exactly how he worded that note.
Writing grows with kindness.
Someday, when you're ready (and you'll know when you are), there will be lots of time for people to take your work apart and tell you why this character's arc doesn't make sense, and why your passive verbs are dragging the whole thing down. If you get to the point where you're ready to publish, a professional editor will gladly help, and will make your work better in the process.
But if you're not ready for that right now, seek out places where kind people will help you grow. The places where you can admit when you're struggling, or where you can say you're pretty sure the thing you just wrote is shit, and the people around the table (virtual or in person) won't agree with you. They might even point out the things they loved.
Kindness will help you find your voice.
I have always been a writer, but I haven't always written. Sometimes life gets in the way. For a while, I tried to be a Serious Scientist™. For a while I contented myself with writing government manuals and environmental reports. But, when the call to write stories got too loud, I found kind places to start over from. I found Firefly Creative Writing in Toronto (whose awesome feedback manifesto inspired this post). I found groups online with kindred souls who focused on what was working, and not on my propensity to forget that questions marks exist in my first drafts.
All manuscripts can be fixed in revisions. Drafts can be torn apart and stitched back together into something stronger and better. But patching up the tender writing heart broken too early by harsh criticism is a much more difficult task.
If you're just starting out, find the kind place to write. The places that will let you dabble and play. The places that talk about voice and heart, not structure and archetypes. Build the confidence you need. Take your time. And if you never leave that kind place, well, doesn't that sound like a cozy place to stay as a writer?