Sagging testicles; What is the cure?

I am not sure if you can be objective about the whole thing. It is always that our problems are the worst and I am not just saying that. Testicles just sag, in some men more than the other. It all has to do, like you said, with lowering temperature and sperm production.

If your testicles are shrinking in size (without being returned to normal) then this is serious and should be looked at.
However, if you have no other problems and you are going through puberty normally, don’t have any problems with erections, and developing, I would say you are fine.

If you can’t put your mind at ease, the only thing that is left to be done is to see a doctor and have it checked. You may have to have a blood work done if he suspects something and undergo other tests or he may just determine everything’s ok just by having a look and touching them.

Don't worry about how far your eggs hang. Stay away from any surgery that will cut into your sack. Every mans sack is different because our eggs are different.
I wear one of 2 jocks/cups 95% of the time. Get one, or more.
During the day my eggs, like yours, are constantly moving because our sacks adjust for temperature and our needs to penetrate and especially drain our wads of sperm. That's the only reason we have our eggs - to make and drain sperm.
i wear my tight jock when im driving a lot or working physically alot. That design keeps both eggs pulled up and held on either side of my shaft. Plus it holds my shaft head pointing up , so when it extends out, preparing to f**k, the head just slides up my belly and my eggs fill. When the urge passes, my eggs never move. They are fuller but still pulled up.

Sometimes you might want to wear a plastic cup if you're planning to do some activity where your eggs are vulnerable to brusing.

Women with big or heavy or sagging tits need different bras to lift and hold them up and out. Men are no different needing special support.

Enjoy having big low balls and teach your women how to stimulate them for more sperm production and larger loads.

Enjoy
Because your sack is big, your job that a lot of men don't have is to protect the eggs when you let them swing or when you walk or f**k.

I have just recently noticed that my balls hang considerably low! Is there anything that I can do to prevent them sagging anymore or make them no sag at all?