Colloquial language: "old fart" Creates humour as well as being an understatement which makes him more approachable.
Parallelism, contrastive pair: "(that would be me) and (that would be you)" brings a sense of liveliness and humour to the speech.
Humour through anecdotes, hyperbole, rhetorical question: "So: what do I regret? [...] I don't even regret that"
Noun phrase: "what I regret most in my life are failures of kindness" centre of the speech and with the superlative it elevates the moral of his point
Syndetic listing of triads: "dogs and swing-sets, and the State of Nebraska and low-hanging clouds and you know other people" creates a sense of familiarity for the audience as they would've experienced one or all of those things.
Metaphor: "in our hearts" creates an emotive tone
Syntactic parallelism, anaphora: "High kindness periods and low kindness periods" the syntactic parallelism stresses the anaphora "good" which is backed by examples to emphasise his point.
Colloquial language, idiom "we get our butts kicked by real life" creates humour
Engages the audience by referencing someone they would know: "The great Syracuse poet Hayden Carruth"
Synthetic personalisation: "you" comforts the audience as they enter the world of adulthood and can live their own lives to the fullest as they start the next chapter of their life
Repetition: "we" the inclusive pronoun allows the audience to feel included as well as unifying everyone.
