It's been mind-buggeringly cold in Joburg these last couple of weeks, and we're just not set up to deal well with it. But I've been experiencing a much greater sense of physical well-being and clarity of mind over the same period. And no, I'm not a Troll.
I'm putting it down to an increased frequency of meditation sitting; specifically, Vipassana meditation, in which one just sits, watches the thoughts as they arise, and lets them go. It's much less of a mental strain than Shamanic Journeying, and so I've found it easier to do every day. and this may have made the difference.
Five to ten minutes every day, that's all. Light candles,ground and centre, sit down before altar. Call quarters if it makes you feel more secure (although I use a much abbreviated form for this meditation), close your eyes and watch. Your mind is amazingly tricky and will try to distract you using every sleight of hand in the book. Don't pay it any mind - just look at those thoughts forming, watch them as they arise, let them go. It's really not difficult at all, and just a few minutes of this clears your mind really well. I recommend this as an everyday practise - plus, it's non-religion-specific.
Here's a good teaching video, too.