Among the preposterous ideas drummed into us as children is the notion that it's inherently good to finish what you start. The most common manifestation of this is the "starving children in Africa" argument for clearing your plate - a line of reasoning so absurd that you wonder whether being three was really a good enough excuse for not getting wise to it. Next time you hear a politician say of some disastrous venture that it's "important to see the job through", it's worth reflecting: is this person just locked in some childhood psychodrama, endlessly playing out a moment when they got a slightly underwhelming lollipop for finishing their food at Little Chef?

Several productivity experts say they've hit on a better approach, borrowed from wartime medicine. "Triage", in its original form, was the battlefield surgeon's practice of quickly dividing the wounded into three groups: the ones who'd die even if they got medical attention, the ones who'd survive even if they didn't get any, and the ones for whom medical attention would make the difference between life and death. With limited resources, it makes sense to focus on the third group. And, if you'll pardon the tasteless transition from the horrors of war to the "horrors" of modern living, it's the same with your to-do list. For example:

1 Email: if you've been following this column's advice, you'll have a spotless inbox. If you haven't, here's a brutal but liberating quick fix: assume that any emails older than three weeks are "dead" or non-essential, and scoop them into a folder labelled "backlog". Now forget about them. For ever. (If the senders needed a response, they'll let you know. But they've probably forgotten, or found another solution to their problem.)

2 Half-read books: if you've neglected a book for more than two weeks, and it's on your bedside table only out of guilt, shelve it, or give it away at bookcrossing.com.

3 Personal projects, hobbies, etc: the most insidious kind of to-do list clutter are the things you started only because you wanted to, not because you had to - except that now you don't want to do them any more. Junk them. "Practising triage is extremely challenging because it requires saying 'no' again and again to what you may feel are good causes," writes the blogger Steve Pavlina. "It's the time management equivalent of saying 'no' to wounded people calling for help."

4 Friends: another piece of advice from Pavlina. If there are people you need to summon up the effort to contact every few months - if it's become a mutual chore to continue the framework of a friendship, without any substance - try stopping.

We feel bad about abandoning things - it's our childhood training - and, like children, seem to feel we need permission to do so. Therefore, as a random newspaper writer you've never met and have no reason to trust, I'd like to say: you have my permission. Also, I spoke to the Dalai Lama, and he said it was OK, too.

oliver.burkeman@ theguardian.com