[ethereal]

There are a lot of books by Mantak Chia who is a well-respected Taoist master specializing in sexual energy transmutation, if you're interested it'd be worthwhile to check them out.

However, I feel that sexual energy is a subset of a greater energy system (Kundalini), under a more spiritual context. After undergoing serious spiritual work it seems like my sexual energy (2nd chakra) is automatically being transferred up into higher chakras, without undergoing any deliberate energy work per se. Napoleon Hill, in his chapter, is most likely describing the transmutation of 2nd chakra sexual energy into 3rd chakra energy (mental functioning, power, control, self-esteem, career, success).

Anyway, a very easy way of transmuting sexual energy is just to not masturbate at all (sex should be ok, though). Another is to meditate and to use the "Bandha technique", which is to visualize and breathe the energy in the lower chakras up into the higher chakras. But a more long-term and permanent advance in transmutation of sexual/spiritual energy is to undergo dedicated spiritual work in whatever form appeals to you the most.