I am so glad that I have an easy answer for you. I am a 72 year old lady who has been doing hot/cold showers for other reasons but they definitely have a favorable effect on my libido. You can search for the way to do them, but you start with water as hot as you can stand. Then you use water as cold as you can stand. You do seven repetitions and end on cold. You can look it up on Dr. Richard Schulze 's forum.
It works if you do it every day and especially if you do it twice in one day. I was amazed.