What does the last paragraph, in which Micawber drinks punch "with an air of great enjoyment", suggest about…

‘My dear young friend,’ said Mr. Micawber, ‘I am older than you; a man of some experience in life, and—and of some experience, in short, in difficulties, generally speaking. At present, and until something turns up (which I am, I may say, hourly expecting), I have nothing to bestow but advice. Still my advice is so far worth taking, that—in short, that I have never taken it myself, and am the’—here Mr. Micawber, who had been beaming and smiling, all over his head and face, up to the present moment, checked himself and frowned—‘the miserable wretch you behold.’

‘My dear Micawber!’ urged his wife.

‘I say,’ returned Mr. Micawber, quite forgetting himself, and smiling again, ‘the miserable wretch you behold. My advice is, never do tomorrow what you can do today. Procrastination is the thief of time. Collar him!’

‘My poor papa’s maxim,’ Mrs. Micawber observed.

‘My other piece of advice, Copperfield,’ said Mr. Micawber, ‘you know. Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness. Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery. The blossom is blighted, the leaf is withered, the god of day goes down upon the dreary scene, and—and in short you are for ever floored. As I am!’

To make his example the more impressive, Mr. Micawber drank a glass of punch with an air of great enjoyment and satisfaction, and whistled the College Hornpipe.