A while ago, I discovered that I could hold back some bodily fluids from, umm, ejaculating. It was basically the same thing without the whole mess. I found that I could do it better and better to the point that nothing came out.
I haven’t experienced anything bad as of yet, but I’m can’t imagine holding something back like that could have zero consequences.
The fluid just backflows into your bladder, and is released the next time you pee. I’ve never heard of any bad medical effects from retrograde ejaculation, so if you find it enjoyable, go right ahead.