I'm 49, I started several years ago when my kids started playing, I wanted them to like baseball, but they didn't. I learned by osmosis by playing pickup with a variety of players, some of whom are coaches and trainers, some of them with high school, college, and even pro experience. I've been in a few leagues recently. O30 mens and O18 co-ed as well as 018 mens. My problem is, I only have so much sprinting I can do. I'm a large dude, 6'2'' 230lbs who can run fast, although not athletically. so I can sorta cover the other teams flash forward for a bit, but I will run out of gas suddenly and need a sub running at that pace. I mean I'm flat out done running for a bit, and can't even catch my breath to talk. Sometimes they don't see me coming for a sub out and get mad, but If you need a 49 year old man to do the hard defending for you, then your probably going to get beat anyhow. I also play ultimate frisbee pickup and run on the treadmill at planet fitness, but playing sports is far more motivating, so get out there and play!