Motivational Speech (Acquisitions Incorporated, p. 77) says that you inspire a group of people to greatness.
You address allies, staff, or innocent bystanders to exhort and inspire them to greatness, whether they have anything to get excited about or not.
Motivational Speech further grants specified statistical benefits attributed to what inspiration entails:
Choose up to five creatures within range that can hear you. For the duration, each affected creature gains 5 temporary hit points and has advantage on Wisdom saving throws. If an affected creature is hit by an attack, it has advantage on the next attack roll it makes.
But is not explicit about what greatness entails. So what does greatness entail? To which greatness are you inspired? Is the greatness chosen by the caster, the DM because it is DM-fiat territory, or by some other circumstance?