In philosophy, Goethendipity, a portmanteau of Goethe + serendipity, is a principle which states that if one has a plan or a dream, one must act on it; one must resolve oneself to carry it out. Once that resolve has been taken, events will move in one's favor. It is serendipity with plan, vision, and intention.
The principle was conceived in the early 1990s by English accelerated learning expert Tony Buzan who, on a trip to Africa, was invited to speak on the development of genius on a radio show, and to explain to his interviewer that it was not ‘luck’ or serendipity that had brought the two of them together, but Goethen-dipity that had brought them together, a term themed on the following quotation by German polymath Johann Goethe: 
“Until one is committed there is always hesitancy, a chance to draw back. Always ineffectiveness concerning all acts of initiative and creation
. There is one elementary truth—the ignorance
of which kills countless ideas and splendid plans—that the moment one definitely commits oneself, then providence moves too
. All sorts of things occur to help one, that would never otherwise have occurred. A whole stream of events issues from the decision, raising in one’s favor all manner of unforeseen incidents and material assistance, which no man could have dreamed would have come this way. Whatever you can do or dream you can do, begin it. Boldness has genius
and magic in it, begin it now.”
— Goethe (1832), Faust
The passage, supposedly, comes from part two of Goethe’s Faust, via extended translation elaboration. 
Another version of the same principle seems to be found in American business mogul Warren Buffett's favorite book One Thousand Ways to Make $1,000 dollars, that he read as a youth—the central advice of which was to "begin, begin" whatever scheme one might, but, by all means, not to wait. 
The following are related quotes:
“There’s something magical in movement, in action — it allows you to ‘think’, to discover new ideas, and to feel like you’re making progress. Don’t sit around waiting — act.”
— Hamdi Ulukaya (2017) 
1. Buzan, Tony and Keene, Raymond. (1994). Buzan’s Book of Genius (pgs. 45, 164). Stanley Paul.
2. (a) Goethe (popular quotes): Commitment – Goethe Society of North America.
(b) Goethe’s Faust – Wikipedia.
3. Lowenstein, Roger. (1995). Buffett: the Making of an American Capitalist (pg. 16). Broadway.
4. Adams, Susan, et al. (2017). “Lessons and Ideas by The 100 Greatest Living Business Minds”, Forbes 100th Anniversary Issue (pg. 116), Dec 18.
● Goethendipity principle (Dutch → English) – JWGoethe.org.