Don't waste your time overthinking and analyzing why it didn't work out.
Why your book didn't sell.
Why no one liked your blog post.
Why no one watched your video.
Listened to your podcast.
Or downloaded that album.
And instead just focus on writing your next book.
On publishing your next blog post.
On recording your next song.
On painting your next picture.
Or uploading your next video.
Because that's the best and probably the only kind of marketing that still works these days...