Hello. Hopefully someone can make use of this information I'm going to share.
1: Hypothermia can occur at any temperature below 60F in water, or 50F in the wind. Look up "water temperature hypothermia" to find more information on what to expect from different temperatures.
2: 44F, as mentioned in the OP, is technically enough for hypothermia to set in, though it will take around 1 to 3 hours to actually die from it, in the best circumstances. What matters at this rate is if you're in water/wet, and how much time you have on your hands.
3: A way to quicken the process of hypothermia while limiting discomfort at the same time is to get drunk. Alcohol is a vasodilator (it expands the blood vessels), which brings the blood from your vital organs closer to the surface of the skin, which in turn cools down faster. Some over-the-counter medications and even caffeine can achieve this affect, although to a lesser extent.
4: In my own experience, hypothermia is NOT VERY PAINFUL. The worst thing about it, in my multiple experiences over the past few Winters, is the wind blowing away any warmth I have, on top of resisting the urge to go back inside.
5: You WILL experience discomfort, and even a burning sensation depending on how far you are into the hypothermic process, but most of the pain will be mental. The discomfort ranges from mild to severe and stems from, well, being outside in the cold water and wind. It's not fun, but it's not impossible, either. The burning sensation is from your body getting too tired to continue vasoconstriction (tightening of the blood vessels to keep vital organs warm), and the gradual rush of blood to your extremities is a bit shocking and almost comforting.
6: You will eventually go numb during the process, starting from your extremities (fingers, face, toes) to your limbs and chest. You'll take more shallow breaths as your body and brain cool down.
7: Extreme coldness is not a requirement for hypothermia. Some may take the term "freezing to death" literally, in that you get frostbite - which occurs below the freezing point, is PAINFUL, as your skin and tissue begins to die. If you want to go this route, that's up to you. It doesn't usually get that cold over here where I'm at.
8: If you want to maximize your chances to CTB, you'll want to at LEAST be in a body of water for as long as you can handle. When you think you can't handle it anymore, you can get out of the water (don't dry off) and let the wind chill + loss of heat from the environment do the rest for you.