Cold harsh truth 8, you have no idea how young you are now, how vibrant, how energetic. Revel in it as much as you can, I guarantee that you will look back on your 40 year old self with both envy and dismay, envy that you want to relive those youthful years with full appreciations, dismay that you didn't. And a warm and comforting truth; most people are happier with each succeeding decade;)