Well, I got a pile of rejection slips (geez, I was only 19), but the nicest rejection I got was from Julius Schwartz, top editor for DC comics, for my Superman story. I had sent a properly typed story, with panel breakdowns and a couple of inked pages. I received a really encouraging letter from Schwartz along with a photostat (anybody remember those?) of cartooning tips by Joe Kubert, which was also showing up in print in comics at that time.
Cartooning is a very difficult sport, but if I'd stuck with it I may have made a name for myself, somewhere, somehow. As it was, my number (50) came up for the draft, wherein I joined the army. I was placed as an illustrator (Military Occupational Specialty: 81 Echo), where I learned the trade on a fast track, starting as a combat artist and graphic journalist.
Subsequently, as an illustrator for 40 years, I got to draw a few cartoons along the way, but nothing like I once dreamed of.
I admire all of you professional cartoonists and all the work (and focus) that it took to get where you are.