The installation of a pull-up bar on my school run route last year started a “challenge Daddy” thing with my kids where they joyfully count reps as I huff and puff, lugging my beer gut into the air over and over again. As I could barely manage 10 when we started, I set myself a target of 20 by the end of 2015. I achieved that by March and slowly crept up to about 24 by the summer. Last month I decided to reset my target to 30 and managed 32 last week. This morning I was disappointed with 29.

The psychology fascinates me. I quickly met my original target and was then happy to coast until I set another target – unthinkable this time last year – and easily met it again, hardly noticing the extra effort.

A sustainability manager I was interviewing a couple of weeks ago (for an exciting client project you’ll hear about next year) used a high jump analogy for this. You have to be able to see the bar to clear it. If the bar was replaced by a laser detecting how high you jump, you would never manage the same height. In the same way you need clear, ambitious sustainability targets, and, when you hit them, raise the bar or the organisation will coast.

That sounds obvious, but I’ve been reviewing the new UN Sustainable Development Goals for the next edition of Ask Gareth, and, of the 169 ‘targets’ only a minority are quantified. “Substantially increasing the share of renewable energy” is highly unlikely to drive change (and provides plenty of cover to justify poor progress).

So set the bar, and if you clear it, raise it.