Your customers, followers, fans all want to know, at a fundamental level, "What's in it for me?!"
The answer is your unique selling proposition (USP), your ultimate customer benefit, and the reason why your customer should buy the product - and buy it from you.
The answer may be tangible like "best price" or "ability to do X" . It might be something more fuzzy like "gain confidence" or "feel good about yourself." Whatever the answer, along with the supporting facts to back it up, is essential to creating an effective message.