Masturbation changes your testostron levels, so I some cases that might be beneficial. Cold showers influence your metabolic rate, so they can help with weightloss.
Sleeping on the floor may be better for your back, but honestly I don't know.
If you want to speak "honestly" . . . everything you just said was pulled out of your ass.
Cold showers may influence metabolic rate but their most pronounced effect is that they make you want to avoid taking a shower, resulting in stinky, anxious, unhappy people.
Masturbating is so much fun than any health benefits or detriments are irrelevant. It increases quality of life.
Sleeping on the floor may be better for your back, but honestly I don't know.