If not know when?

The phrase is not now, when means if you are going to do something and you can do it, why wouldn’t you? Many people who want to do things in the future don’t always do it. If you don’t do something because something is holding you back think about what is more important. The thing holding you back or what you want to do? If you want to do something do it. You shouldn’t let anyone stop you from following your dreams. Many people say they want to do things but they don’t have time for them. If you really want to do that thing, whatever it is, you should make time for it otherwise it’s not that important to you. If you really want to do something do it because if you don’t you are going to spend your entire life wondering what it would have been like.