The most important thing I have learned from starting startups is something I call "business mindset". "Business mindset" is is the act of guessing what someone wants and then offering it.
This is best illustrated in the world of dating.
A date proposal must be concrete. "Would you like to go on a date?" is unacceptably vague. "Would you like to have dinner this Friday at 7pm at Jade Garden?" is a good starting point for negotiation.
Proposals are negotiations. A negotiation ends when both parties agree or walk away. Abstractions are inherently vague. Accepting "a date" could mean anything from "a 15-minute coffee" to "an entire day in Vegas". It is impossible to accept such a vague offer.
If your prospect is busy this Friday at 7pm then she will propose an alternative time. If your prospect does not like Chinese food then she will propose an alternative restaurant. If your prospect says "I am busy this Friday at 7pm" then that does not mean should propose an alternative time. It means she is not interested in dating you.
"Business mindset" is different from "employee mindset" because in job hunting you have little power. If you have a lot of leverage then you can ask for small changes to salary, position and perks. That is about it. You cannot negotiate far from where the company has already decided what they want and what they are willing to pay.
"Business mindset" is different from "engineer mindset" because in the engineering universe, right answers are determined by science. In "business mindset", the right answer is determined by the people who accept your terms. An operation where 100% of the population loves you—but not quite enough to pay you money—is not a business. A business where 0.001% of the population pays you money and 99.999% hates you has 78,000 customers.
Nobody else's opinion matters. Scientists' opinions do not matter. Media's opinions do not matter. The public's opinion does not matter. God's opinion does not matter unless He paying you.
"Business mindset" is a creative activity. Everything is negotiable. Marketing is about raising awareness for a fixed product. There is no negotiation with customers. In marketing, business mindset is applied to influencers instead of customers.