Is masturbation is good for your health?
It's certainly not bad for you and yes, there's lots of evidence that sexual activity, including masturbation, are good for your health. For men there's evidence that frequent ejaculation lowers the risk of prostate cancer. For everyone there's evidence that sexual arousal and orgasms mildly boost for the heart and immune system.
On a personal level I'm over 50 years old and I've masturbated once or twice a day since I was a teenager. I won't say that's what's helped me stay healthy all these years because it could be other things like a healthier diet, getting better exercise, reducing stress in my life, or any of a thousand other possibilities. But I will say I'm in much better health today than I was in my teens.