Turning 40 is a huge milestone in any person's lifetime, and A Subtle Revelry knows the struggle is real when it comes to choosing a birthday gift for someone whose fortieth birthday is coming up. To that end, we've put together this great article on numerous 40th birthday gift ideas for both men and women. You can also have a look at the idea for a 40th birthday care package gift idea as well as other special and unique 40th birthday gift ideas. Read our entire article here to find out…