The uncomfortable sides get balanced out by the benefits. You can see that in the correlation between the duration of a streak and the amount of benefits happening. Experiencing an urge is mostly perceived as an uncomfortable feeling, but that same uncomfortable feeling can actually be a good one, and make everything more interesting. It comes down to how you perceive it, mostly it gives off a fear that it will become more and more difficult to keep it up. And that acts as an obstacle to continue the streak. So gain trust that you can flip the perception from something only increasing in difficulty, into something that will make everything better, replacing that fear by the increased confidence. Of course the same uncomfortable sensation will still be there, but simultaneously with the excitement of what it will offer. The fear of the first mentioned case creates avoidance behaviour by ending the streak to get rid of the ongoing sensations, but the latter motivates you to keep getting more of that uncomfortable sensation, an upwards spiral. I describe an urge as a sensation that actually starts as pleasurable, but at the same time calling to be processed in some way. So when you want to do semenretention/NoFap, that creates a problem. That's why it quickly becomes an uncomfortable feeling. But the thing is that the feeling that it has to be processed in some way, is what can act as the motivating feeling. Processing in some way doesn't necessarily have to come down to fapping. It means there is some energy that has the potential of creation. The fapping is a short circut of it. So that feeling can make you look forward to have more of it, instead of relapsing. Resulting in the streak continuing.