It doesn't have to hurt

Behind the threshold there's often a second belief, about effort. It says that exercise only works if it's hard, and that you should finish red-faced, gasping and wrung out. By that standard ten minutes at a pace where you can still hold a conversation is a stroll. Meanwhile the full session is something you half dread, which is another reason it gets cancelled so easily.

Panteleimon Ekkekakis, Gaynor Parfitt and Steven Petruzzello reviewed 33 studies on how people feel during exercise at different intensities. The picture is consistent. There's a level of effort that physiologists call the ventilatory threshold. It's roughly the point where breathing becomes laboured and talking gets difficult. Below that level, most people feel better during exercise than they did before they started. Around it, people vary a lot. Above it, nearly everyone feels worse, and the harder they push the worse they feel. The reviewers also note that when people choose their own intensity, as opposed to having it set for them, they tolerate harder efforts better.

They draw a conclusion that I think is important and that the fitness world has been slow to take up. Most advice about exercise treats the decision to do it as a matter of weighing pros and cons. But people are also steered by how exercise felt last time. If it was unpleasant, some part of you will resist doing it again, whatever your reasoning says. The reviewers argue that guidelines should consider whether a given intensity is likely to increase or decrease pleasure, alongside whether it's effective and safe.

Think about what this means for someone with the threshold habit. Your picture of proper exercise is hard and long. So your memories of exercise are of something that mostly felt bad while it was happening. At twenty to seven on a Tuesday, the part of you that remembers that isn't keen. The harder you've made your full sessions, the easier they are to cancel. I'm interpreting here, but it follows from the review.

Ten minutes at a moderate pace sits well below the ventilatory threshold for most people. By the evidence of that review, it's likely to feel good while you're doing it, quite apart from how you feel afterwards. And you'll want to do again what felt good last time.

This connects to a study of how exercise habits form. Navin Kaushal and Ryan Rhodes followed 111 new gym members for twelve weeks. Several things predicted whether exercise became habitual. Consistency was one. Another was low complexity, meaning a simple routine. The setting mattered, and so did what the researchers call affective judgments, which means whether people found it enjoyable. They concluded that trainers should keep things fun and simple for new clients and focus on consistency. In their data, exercising at least four times a week for about six weeks was the minimum for a habit to take hold.

Ten minutes fits that description closely. It can be done often, it's simple and it's pleasant. It matches what that study says builds a habit far better than an ambitious programme does.

I should deal with the objection that easy exercise is pointless. It isn't, and chapter 3 showed that. In Ekelund's accelerometer studies, activity of any intensity was associated with lower mortality, light activity included. Harder exercise does give more benefit per minute, and the NHS notes that 75 minutes of vigorous activity gives similar benefits to 150 of moderate. If you enjoy working hard, work hard. But hard isn't a requirement for it to count. If hard is what's been putting you off, you can drop that requirement and lose very little.

One practical note. Go by the NHS test. If you can talk but couldn't sing, you're at moderate intensity and you're doing it right. If you can't get a sentence out, you're above it, which is fine if you like it and unnecessary if you don't.