In the last few days (following the start of my membership - see Introduce Yourself entry) I have seen many references to the need to warm up/down the penis before and after exercise, and various techniques for doing this.
For many years I have had access to a bidet in the bathroom, and have found it an excellent means of achieving penile warmth. NB: it is important that the bidet has a mixer tap, mounted on the rim, with a directional, adjustable nozzle. Two minutes use with an increasingly hot water stream directed over the penis produces a really great result.

Bidets are not expensive, and are in my view essential in any case for anal and genital cleanliness.