Hi Chris,   The biggest difference I felt quickly was less pain "in my bones."  I was much less achy and sore.  I'm not sure that getting my D levels up has effected my depression or anxiety levels, but I've tackled those for years. Fortunately, antidepressants are effective for me.   My fatigue is less now than it was back in 2008, but I've made other changes since then which probably made the difference.   It's great that you are feeling better!!  Whether it's from the vitamin D or anything else, good for you.    One thing I will do more recently is, if I begin to feel a little sick (ie. catching a cold), I will take extra D and it seems to help.    Hope you continue to feel better and better!!