I’m 15 years old, and I play against 18-40 year olds. Is that good? Also, I weigh 80kg. Is that healthy at my age?
Let me take your question in two parts.
First: Is it good for a 15 year old to regularly play against 18-40 year olds? The answer to that is “it depends.”
Fifteen is generally the exact age where it is considered ok to play out of your age range. It’s generally not good for anyone under 15 to play competitively against older players because they usually don’t have the physical development of the older players. Since growing bones, muscles, and ligaments can be more fragile, you can be more apt to injury. Therefore, they can be at a disadvantage size and strength-wise.
Some leagues offer 15 and up divisions, and it’s not uncommon for good, young players in high school to play against 18 and sometimes 19 year olds.
As far as whether or not it is “good” for you, what you should consider is the other players’ skill level. Here is a simple way to figure out if you should be playing with them:
Below your skill level = bad
You may have the fun of being the best player out there, but you are not pushing yourself and not learning how to adjust to players that can do things you can’t.
Around or slightly above your skill level = good
Obviously you’ll have to push yourself harder and you’ll probably have fun doing it.
Far above your skill level = bad
You’ll be at a disadvantage. While you will have to push yourself harder, you will likely be a detriment to your team (if you play – and not playing doesn’t help you) and being outclassed might also destroy your confidence.
Eighteen to forty is a broad age range, so I suspect there may be a mix of skill levels. The key is to play against people that you can learn from, that are good enough to make you push yourself to become better, and that you have fun playing with and against.
Of course, your physical development can also determine whether it’s “good” for you to play older competition.
That gets us to your second question.
You indicated that you weigh 80kg (that’s about 176 pounds here in the U.S.).
It’s really impossible to tell for sure without knowing at least your height, but I suspect you are bulkier than most kids your age. Basically, being a heavier player in good condition can be good; being a heavier player in bad condition is bad.