I believe that this is more alongside the lines of "Don't focus so much on the future that you miss out on the present".
Many of us give up plenty of chances to do things because we worry about the future and possible occurrences, yet in doing so, we sometimes deprive ourselves of the drive we need to keep ourselves at 100%; Nasa is living in the present, enjoying every single minute he has with his beloved and simply leaving future possibilities as just that, things that may or may not happen in the future.
Not to demean the greatness of preparing ourselves and planning ahead, but let's not focus on it so much we lose the spark of creativity and impulsiveness that makes us ourselves, that make us happy... that makes us human.
After all, if we truly worried about the future as much as we'd like to pretend we do, we wouldn't be otakus and reading mangas in the first place wouldn't we?