Table 2 Barriers: Themes and illustrative quotes mapped to COM-B

Capability - physical

Health problems, illness, injury, pain

Physical limitations

I have a back injury and a neck injury. That stops me from doing short, sharp movements. I tend to try and just work through the pain if I’m doing something. If I’m walking or bending and I get pain, I tend to just try and work through that pain. I've got to admit that I don’t necessarily put myself in that same position again, to avoid going through that pain again (Female, age 61, good health, very overweight*, FG13).

Young (FG3, FG10, FG19)

Middle (FG6, FG7, FG9, FG16)

Old (FG2, FG13, FG17)

Capability - psychological

Perceptions of aging

Given my age, I'm thinking, "Well, you know, do I really need to keep my, um, exercise up, and... and my routine, because at the end of the day, is it going to help me?" (Male, age 59, good health, slightly overweight, FG9)

Middle (FG6; FG9)

Old (FG2, FG14, FG17)

Unsure of benefits, unsure of how much to do, unsure of how, unsure of how to gauge intensity

Need for knowledge

But maybe, that’s what I need to do at the end, at the, make the, the walk up the hill at the end of every, um, every walk. Make sure that that’s what I do, just to bring that last bit in. I mean, high intensity, for how long? How long are you supposed to do it for? How often? Is it every day? Every walk? Once a week? Um- (Female, age 71, excellent health, slightly overweight, FG1)

Young (FG4, FG5, FG10)

Middle (FG1, FG6, FG9, FG11, FG15, FG16)

Old (FG8, FG12, FG17)

Opportunity – physical

Bad weather, hills, living location, looking for opportunities

Environmental constraints

The mall that’s within two kilometers of my house doesn’t have stairs in it. It’s all on the same level, so that takes stairs out of the equation. I live in a single level house; I don’t have stairs. It puts you in a bit of a dilemma with regards to a lot of the stuff. From what I can see, you’re asking us to do this stuff, or about how to do these things, which I’ve always done (Female, age 60, good health, slightly overweight, FG13)

Young (FG3, FG4, FG5, FG10, FG18, FG19)

Middle (FG1, FG6, FG7, FG9, FG11, FG15, FG16)

Old (FG2, FG8, FG12, FG13, FG14, FG17)

Motivation - automatic

Perception of low fitness or strength, body weight, dislike being out of breath

Perceptions of effort and energy

like if you’re over exhausted at work, even though my work is mostly sitting down because I work at office and you know, you had such a hard day. And you have customers etc, etc and yeah you come home. You don’t want to do anything, you don’t want to move yourself. Even though you weren’t moving as much, you know. That’s prevent me. I think the daily stress, daily stress and busyness it prevents me from ah, you just want to lay down in a bed and watch TV or something just to you know, distract yourself from the stresses. I think the stresses play a big factor as well (Female, age 44, very good health, slightly overweight, FG4).

Young (FG3, FG4, FG5, FG10, FG19)

Middle (FG1, FG6, FG9, FG16)

Old (FG2, FG12, FG14, FG17)

Fear of injury, fear of falling

Fear

Yeah, we go high intensity with the fast walking. I'm always a bit worried, if I really up my pace with my walking that I’m gonna stumble and fall. I don’t know, I can’t run. I've never been able to run, never been a runner. But I can step it out, but I, if I’m gonna do the high intensity and really go fast, I'm really at risk of, I feel like I’m gonna fall (Female, age 71, excellent health, slightly overweight, FG17)

Young (FG10)

Middle (FG6, FG16)

Old (FG2, FG8, FG12, FG17)