It’s time for a little gratitude. Every time I do one of this week’s core exercises, I am intensely grateful that I am not doing planks. Even when the moves are hard, it’s OK, because at least they aren’t boring.

Perhaps my favourite moment of the Lifehacker fitness challenge so far was the day that we were done with the plank challenge. I hate planks. Luckily, it’s possible to work out your core without having to do a single plank.

Video: The plank is a great exercise for your core, but holding it like a statue is only one of many ways to work those muscles. This video shows a plank-based exercise you probably haven't seen before -- and it's great for your obliques.

We've told you how to do planks, and why to do planks, and what to do instead of planks when you get bored of planks. But there's a critical thing about planks we forgot to tell you: You don't have to hold the position until you collapse.

The L-sit is the motherlode of core exercises, and requires a combination of strength, flexibility and control in your arms, shoulders, abs, back and legs. They're tough, and require some working up to, but they're oh so good for you.

Planks are a simple bodyweight exercise that challenges you to hold your body as stiff as a board for as long as you can. It's sort of become a badge of honour to be able to hold it for 60 seconds or longer. But if you're holding it for aeons without the shakes, you're probably not working your core as you should.