Sometimes. I'm doing medicine and when you learn about all the diseases and when they can strike, plus you see young people who are seriously ill, it makes you realise how precious life is and how short a time we really have. I'm in my early 20s but feel like the last 5 years has passed in a flash. Most people don't appreciate the freedoms of youth - I don't mean looking young (although its nice), but, for most people (not all unfortunately), the freedom of mobility, of being able to get out and walk and run and do sports, of having your senses for the most part intact, of being able to see details and hear music to a level of intensity that will eventually fade, to have so many opportunities ahead of you. We sometimes get so bogged down in the minutiae of life that we forget how lucky we really are.