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The yang power of the kidneys is primarily ruled by Mars. Venus impacts the yin side, although it is the vital aspect of Mars which powers the health side of the kidneys, both yin and yang. The Sun empowers everything, including both one's Mars and Venus energies, but working on your Mars will give the most direct results as far as kidney weakness goes.
For health, HPS Pythia has listed vitality as a spiritual aspect, but I have seen it go either way. I know of members who have done material squares for health, and I have done spiritual ones for health and have gotten good results.
Mars is currently in Gemini, but this would still give some result if you used it specifically for health. Otherwise, either use Thurisaz on a good date. March 6th is a great date, and March 5th is also an example of a good date.
Mars in Leo can also be used, starting on May 23rd.
Both Jupiter in Aries and Jupiter in Taurus can be done as squares for the purpose of health. I had done an Aries one for vitality and it helped, although it seemed liver focused, rather than kidney focused. This is fine though, because the kidneys and liver are connected in TCM philosophy.
Jupiter in Taurus, and other energies like Venus/Moon in Taurus, and the Sun in Taurus, are useful for health, but these impact mainly the yin side of the body and soul. These are definitely useful in their own ways, but don't ignore the pure fire energies in regards to health.
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The acupressure points are a great way to mitigate some of your symptoms, although acupressure does not raise your total vitality, but it does direct it into problematic areas of the body.
I would look into other yang yoga like the Tibetan 5 Rites, which stimulates both the stomach and the kidneys. This would be a big complement to hatha yoga. Exercise is always the best way to generate more yang energy. You can also look up Kidney/Water element (TCM's element philosophy) - style yoga.
If you ever feel too hot from yang style yoga, then use the acupoints to cool off first. Speaking of cooling off, although the winter time is associated with increased kidney activity, it is ultimately a season of contraction and reduced vitality. This can aggravate existing yang deficiencies.