Retention "re-
tension"
If one tries to forcefully prevent ejaculation it can create "re (more, excessive)
tension" in that part of the body and other areas too. Maybe the word retention is not the best, maybe we could instead say 'opening, tranformation, circulation' etc
One of the mental aspects:
When we have desire, it is a projection outwards. Desire for anything creates a pull of your energy away from yourself, you can actually feel it in your being, it's the begining of loss..........
Most,
not all but most sex acts is based on desire (outward projection, 'wanting something/one') the body simply follows the minds directive and sooner or later forces the sperm out- wards toward the object of desire.
So the mind and it's motives for having sex in the first place are paramount to consider. Is it an outward projection of desire, or an expression of sharing love that is calm, relaxed and full of respect and sincerity? Wanting nothing, not even to 'feel good'.
(this question isn't directed at anyone in particular, it's just handy to consider)
It all starts from the mind and it's motives.
One physical aspect.
If you take the analogy of traffic on the road. When the cars build up at the traffic lights, it causes congestion, especially on a one way street. In order to ease the congestion, we wait for the lights to turn green (is that the colour that other countries use too?

)...........................or, instead getting to the lights, we do a u-turn.
But in order to do a u-turn, we need:
-enough space on the road
-put the car into reverse.
Im not trying to be flippant, but in order to avoid traffic congestion and seminal congestion redirection capacity and redirection pathways are needed.
The redirection capacity is made more efficient by converting the liquid jing into qi (gas). This takes skill and (usually) some time to become proficient at. Specific techniques can be very helpful in this aspect.
The redirection pathways of the body need to be open if the sperm is not to stagnate and congest, otherwise it might be more healthy to allow it to release.
One way of opening up redirection pathways is to practice
dao yin. Daoyin can corect the structure of the body, clear the channels and allow qi to flow.
Massage helps also.
Also, meditation investigating the mind, investigating the body....................internal space, opening, being relaxed, calm, respect, moderation, non-atatchment to outcomes these are all so important, very important.
Actually, when these are practiced regularlly, 'retention' can happen naturally without much effort, because all of the other other pre-requisites are being met.
Don't forget that even if the mental side of the equation is adressed, the body can sometimes take a while to respond to change due to the momentum of past habituations. So many times, seminal emission might still occur. The body might need a little time to adjust, so we should always be kind to ourself. Don't force, don't rush, investigate the mind and motives, open, open open.
Whoa, can't believe how much i just typed