I think our mindset can be the one single most important thing if we want to achieve any of our goals.
Of course, finding the why as you say is useful for maintaining a productive dynamic and keeping our discipline in check. Constantly remembering what do we want to achieve push us to keep going on the difficult days, because with long term goals there will always be some days that are totally crap, and overcoming them is one of the most difficult things we could face in life.
But there is always a way to beat any difficulty there is. I think right now, in the world, there is more opportunities than ever to get ahead in life. All of it thanks to technology and the world of abundance it creates.
Oh, yes, our mindset controls everything in our life. Very important to get your mindset right first. I've written about that previously but wanted to answer the question about finding you WHY after you have the healthy mindset.