New Delhi, Sept. 4 -- The 20s feel like a superpower.

When I look back on my mid-20s as a 40-something writer, I feel awestruck by the sheer recklessness and invincibility of those postgraduate years. Life was not only significantly ad hoc, pinballing from ill-advised impulse to impulse, but also lived without physical consequence. The body, mighty and un-hungover, bounding from one shenanigan to another with the occasional bruise that was immediately shrugged off, made it through without having to think about what it was going through. That unmoustached young man sometimes feels like someone else entirely.

Actually, let me amend that: its consequences, I realise as I embark on my routine of morning stretches that enable me to get out o...