I've tried repeatedly for the last few years to abstain for an extended amount of time without much success until recently. Occasionally an unbelievably intense urge to relieve myself would inevitably sabotage my efforts. Unlike the mild horniness I would encounter during the day, this urge was very negative in that it was like being completely immersed into a full body experience of urgent need. "will power" was just not cutting it. I had to find something to stop the urge.
The solution I've found has put me many strides ahead in this battle, so I feel it would be a valuable thing to mention here. Not only have I exceeded my personal record - I feel as if I could comfortably double it.
Anyhow, I discovered that these intense urges seem to originate in the scrotum. By pressing two fingers into the scrotum, pressing deep between the testes against your penis and vigorously massaging in a circular direction (without inducing pain), you can stimulate whatever nerves are signaling these urges. At first you will notice that a huge wave of additional horniness will suddenly hit you like a brick wall. This will quickly subside, and after a full 2-5 minutes of massaging (it is important to massage for quite a while to make this work), these nerves appear to become overstimulated and stop transmitting "urge signals". The feeling afterwards is remarkably peaceful. Essentially the theory is to allow you to deal with the horniness all at once instead of over endless hours.
Since this procedure usually stimulates a boner, it should be eliminated soon thereafter to prevent temptation from ruining progress. To do this, I use a technique I heard about from a friend. Jump vertically as hard as you can about 30 times. For whatever reason, this vigorous exercise seems to stop the blood flow and return it to a flaccid state fairly quickly.
Hope this works for someone out there - I'd appreciate hearing any feedback about your experiences...