I started because when I hit 50 (64 now) my balls stopped producing Testosterone, which wasn't picked up by Drs for a number of years, and I had to start with T Hormone Therapy.
The first one was Testoderm, 3" x 2" that stuck to the scrotum and why I started shaving as they had to make good bodily contact to work properly. Apparently these were US produced and became unavailable in the UK - they switched me to Andropatch which were a nightmare - sodium hydroxide (NaOH) quite a strong alkali was used to transfer the T sub to the skin anywhere, but after less than 10 days I had 8/9 red raw patches on my skin - hardly surprising with NaOH (thanks heavens I didn't try them on my balls! Back to the Urologist, Nebido was prescribed 1000mg/4ml by injection every 3/4 months into muscle (first supervised by a nurse, then on my own) buttocks suggested, but difficult to self-administer, so I use my thigh muscles - great but I went all adolescent and spotty! So off my own bat, I tried using 2ml every 7 weeks or so, alternate thighs - adolescent acne disappeared, by T -levels are nigh on perfect, without the huge highs and lows. Anyway back to the topic, if you use THT your balls don't have anything to do, so give up completely and shrivel, and had got to the size of small grapes and were pulling back up into the body cavities, where they reside before birth (and sometimes after - undescended testicle/s) and getting smaller by the week, so I tried pulling them down, but only worked whilst I hang onto them, so made a leather harness tight enough to stay above but not strangle them - that gets very painful, very quickly and hung a lead weight on them - but not prctical for public use! I then started digging around on the 'net and found Dave's site and bought a WMC. It seems away from the body's heat helps a good deal and they're a reasonable size now (I'm a nudist/naturist, and happy to display my WMCs - only ever had a couple of double takes and that from younger ladies - late teens/early twenties - probably never such a thing before, one did ask me if they're comfortable to wear, but didn't try to weigh the package unfortunately. Anyway that's how and why I started and now have a good 2" hang without weights in warm weather - plus I like it - my wife doesn't mind one, but doesn't appreciate more! I now feel lost without them, as though something's missing, oh - there is.