Marketers typically refer to this concept in abstract terms without understanding the underlying psychology behind the true meaning.
The reason for creating a positive mindset is because it creates a sense of abundance around an individual, which draws interest and creates opportunity. Here's a link to a fascinating article that explores & contrasts scarcity & abundance in leaders and the impacts they have on their organizations (research article).
There are many marketers, coaches, mentors, and false profits who use / abuse concepts (including religion) to build belief-based systems to help people create these feelings and beliefs of building positivity. Each person has to develop their own sense of belief in themselves and develop a discipline of the mind to build positivity.
Abundance is easy when you have choice and things are going your way. When things get tough (and options and your feelings of scarcity take over), that is when you need to dig deeper and fall back on work ethic and belief that you will turn the corner and create new options to restore your abundance.
From a marketing perspective, it often comes down to meeting with clients (new and prospects), establishing and building relationships, and offering value (find & solve the pain points for customers). This is where we rely on our creativity, innovative thinking, and collaboration to generate options and build positivity and abundance.