You Don't Know What You've Got 'til It's Gone
We all have heroes in our lives. Idols. Whether they are famous or personal to you only. Every day you live your life, and your actions are because of these people. Some people will have first learnt to play guitar because they saw Ziggy Stardust. Other people may decide to attend social events because a friend of theirs showed them that it's possible to have a good time without feeling you're not wanted in those situations.
Our problem, and it's a problem everyone has, is that these people don't last forever. You can wake up tomorrow, and hear the news someone who affected you so much has gone. And what makes it worse is that there will always be one thing that you've wanted to tell them but have never got round to it. Tomorrow makes it too late to say it.
Personally, Lemmy and Bowie weren't massive heroes of mine. But they made up part of who I am in terms of music. But to know they both succumbed to a scum bag of a disease that my own father died of who had a massive effect on my life, is I think the most upsetting part. It's shit to lose your Dad to something as awful as cancer, but it's worse to never have an opportunity to tell them how you feel as well.
So the one thing I think we can all do today is think about those people who are like Bowie to you, and call them or write to them and let them know what they mean to you. Tomorrow will always be too late.