Judge your ideas
Holding an idea in your head is like trying to judge an image by looking at each pixel individually.
Writing is how I test out new ideas. Once the idea is written down, you can take a step back and judge it as a whole and sculpt it to be its best.
Clear writing demands clear thinking, which makes it the ultimate discipline for sharpening the mind. - @Johnny_Uzan
Write often and you'll know it's difficult to write. It's because your mind isn't clear.
Writing is an excellent practice to clear your mind. The end goal is to speak like your write and write like you speak.
Meet interesting people
Writing can be a medium for meeting other people. The more you put yourself out in the world the more chances you have of bumping into others on the same path.
If you're one of these people, please contact me.