I have been studying/experimenting with sexual energy for a couple of years. I made several attempts to do semen retention with varied success. I have done the blocking technique in solo practice (not recommended. It felt uncomfortable and unnatural. I only did it twice before ditching it). I have experienced kundalini syndrome to a limited extent (also not recommended. I felt like I was burning up from the inside). I have experienced blissful energy that crashed into depression after an ejaculation. I have been through phases of loathing sex and phases of craving any and all sexual stimulation. In other words, I have been all over the map for the past two years.
Recently I seem to have settled into a nice, healthy, balanced zone. I am on day 30 of a semen retention cycle and I feel much more relaxed than any of my other attempts. The key is that I have learned to move the energy better.
Sexual energy is potent stuff. If you decide to retain semen then it is going to build up in your system. My kundalini syndrome happened because I was hoarding up sexual energy. There got to be too much of it in my system. It was literally cooking me from the inside. I learned from that experience that energy has to move. If you do not allow it to move in ways that are natural, then it will find unnatural ways to move.
It was karezza that completed the puzzle for me. I knew what semen retention could do. I knew that I could build up huge amounts of sexual energy very quickly if I wanted to. Karezza showed me how to move that energy within my marriage in ways that were highly beneficial for both me and my wife.
I used to think that sexual practices were about building up more and more energy.
Now I know that the energy is not meant to be hoarded. It is meant to be used or shared. I build up yang energy, and I pass some to my wife through karezza. She builds up yin and passes some to me. Neither of us is depleted by this process. Rather, we are balanced by it. The more often we are in loving contact with each other, the better the energy will flow and the better balanced we will both be.
The energy can also flow into other areas of your life (exercise, job, friendships, hobbies etc). If you over heat you can also let it go. You simply put your bare feat on the ground and will the excess energy to move into the ground. I am sure that sounds whacked to anyone who has not experienced it, but it works. The Earth is one big energy sink. People doing solo karezza should try that when they start to feel like the sexual energy is too much.