I am planking at 5 minutes! It's like being 28 again- only I weigh more and I'm more bitter. Anyway. Superb news. I've been combining planking- holding your body weight on your forearms and toes, keeping your body straight like a plank- and reading for some months now. The most recent project was to break my record of 4 minutes 40 seconds.
I started on the 6th January getting 2:17. I pushed it up a day at a time to a frustratingly-close 4:31 on the 25th. Yesterday I managed 5:00 exactly. I've done it through eating chicken and pepper fajitas, tuna sandwiches, early nights, plenty of gym sessions and straight-up persistence.
The book: The Dreaming Void by Peter F Hamilton. I'm 300 pages in, towards the halfway point- it's fantastic so far. I think I'll be able to read it a little faster now that I'm not working out at the same time.