...And I know you're shining down on me from heaven
Like so many friends we've lost along the way
And I know eventually we'll be together...

Your life is not just yours - it is the series of experiences & memories u've accumulated over time, which are also part of the series of experiences & memories others have accumulated. In other words your life is a part of others' lives. Taking away your own life equates to taking away a part of others' lives as well - which is probably the most selfish thing one can ever do.

Life is precious. Cherish it. Even if not for your own sake, please cherish it for others' sake.