Any help for Men's testosterone decline?

I am 43, and live in the uk. and for past 3 or so years i have noticed a sudden( to me) drop in sex drive, vigor and gen zest and focus from my normal self, i did a little Research on the symptoms and have read it could be due to my levels dropping, after blood tests from doc they agree my levels are a little low for my age but not enough to warrant treatment. where as i know in myself i am no where near to how i should be feeling but they wont listen. any help?