I agree with everything Gerald said. With that out of the way, you've not mentioned what work or hobbies you've had prior to your interest in pursuing welding.
If your previous work required a great deal of hand-eye coordination, you have a leg up on anyone leaving a desk job for a trade skill, for example.
I'm 47 also, and find myself paying just a little every day for the foolishness and indescretions of youth. My joints ache every day, sometimes interfering with my performance, I shake like a Chihuahua in a blizzard, and my eyes are not young anymore. This is not meant to discourage you in any way. We have many members here who are learning this craft in their retirement. I just want you to keep your expectations realistic... you may take to this like a duck to water, or you may struggle through the whole course, depending in part on your coordination and in part on your threshold of frustration/expectations.
When I first did industrial construction (while quite young), they paired me with the oldest, crankiest SOB they could find. He was 65 at the time. (Not the oldest welder on the job, just the crankiest old welder.) I presumed they expected both of us to fail, and get rid of us. We got along famously, and three weeks later, the super made everyone else stand down and watch us for an hour, because we were producing almost twice as much work as the other four two-man teams combined. Age is not an obstacle, unless you convince yourself that it is.