It legitimately ****es me off that so many people ask the "am I too old" question when it's been asked literally 3x/month on here for the past 10 years or so.
Not even close to too old. There have been many world champions that started at or after that same age. What do YOU WANT out of boxing? Is it a passion? A hobby? A competitive means of staying in shape? First identify and define what you want out of boxing and apply yourself accordingly. Success in other sports doesn't necessarily translate to success in boxing. Athleticism is just one of the tools in the shed that you bring to war. Boxing is weird in that it balances on a very thin line between sport and straight up combat. This isn't something you want to get into and half-a**. I'm 34 years old and in early February I'll be 35. I started at 18. I was very successful in American football and basketball, and I truly enjoyed them. I'm a strange case in that I got into boxing not out of need but desire. I was a natural athlete and any sport I ever played I was successful in, but I never truly loved or enjoyed sport like I did boxing. Since I started at 18 though, my meal ticket had already been punched with football and basketball and if I wanted to be able to go through college I had to give my time to them and then the military because I screwed everything else I had going for me in life as usual. I always truly regret not going "all in" with boxing. I'm not saying I would have had pro success or anything, but it was my passion. I'm also normally an all or nothing type of person. I'm not anywhere near smart enough to give anyone advice on what to do, but I've made so many drastic mistakes in life yet I'm still here that I can relate my own experiences and try and offer advice from there. Try and identify what you value most and what you want in life and stack the deck in your favor to achieve. Boxing straddles a thin line between sport and straight up combat. After you have started, figure out what you want from it, and if you are willing to put in the work and pay your dues, stick with it. The more and longer you train the more you learn, but the more and longer you train, spar, and compete the more you have to put in to learn. When you begin to feel the taxes outweigh the benefits, cap yourself. If you want THIS - boxing in total, stack the deck in your favor and GET IT at any cost. Bend the rules, whatever. Screw what anyone else thinks, if you can't live without it or you need it to live, do whatever you need to accomplish and achieve what you want.
Start now. I can name countless boxers who have started around your age or even a few years older. Marvin Hagler, Liston, Frazier, Foreman just to name a few.