Table 1. Ambassador motivational strategies and evidence of their efficacy, implementation, and maintenance in the ambassadors plus motivation training condition.

Strategies peer leaders focused on in group walks	Efficacy	Implementation	Maintenance
Get to know the walkers and help them feel at ease (relatedness support)	‘her husband who doesn’t get out much, he was great you know. I think I brought him out of himself a lot’ (Val, 70, ambassador completer)	‘I didn’t notice any motivational things, I just noticed that she [ambassador] walked with a few people just to socialise’ (Beatrice, age 76, adherer)
Help each walker feel like an important member of the group (relatedness support)	Social support ‘I love walking but as I’m getting older, I’m finding that it’s getting a bit more and more difficult, but if you’ve got someone with you, it helps. I prefer to walk with someone if possible and I just thoroughly enjoy it the whole time’ (Enid, age 86, adherer) ‘I just need encouragement to keep going … I enjoyed the company. I felt good about it’ (Henry, age 69, challenged but remained) ‘We were doing it in a team thing. I made sure that I’d be checking up on the others. ‘are you going to walk today? ‘are we going to walk today’? or if they are not, I’d say ‘Well I’m still going to walk’ (Sally, age 80, adherer)
Help make walking more enjoyable (autonomous motivation)	Walking with others ‘I mostly walk alone but I found it very entertaining to walk with other people. More socialising made the walk more enjoyable’ (Elizabeth, age 87, adherer) ‘I enjoyed the company. I felt good about it’ (Henry, age 69, challenged but remained)
Help walkers feel successful (competence support)	‘I think, [name of walker], when she first started, she sorts of lagged behind a bit because she is used to walking at a very slow pace … but she picked herself up … I walked with her the other day, and she said ‘Oh, I’m walking so much faster’. So, she felt very good about herself. You know she feels that she really achieved’ (Val, 70, ambassador, completer)
Provide choice to walkers regarding their walking (autonomy support)		‘We did have one little group that we got going but it was the group couldn’t walk very far with. We had to more or less [walk] partly indoors and then a few times we went around but still in the village, just walking around the streets here where they could sit if they needed to sit’ (Anna, age 74, ambassador completer)
Encourage input from walkers (autonomy support)		‘ … when we knew that she [the ambassador] wasn’t gonna be around, we nominated somebody from the group, each day to be the ambassador and that was quite bit of fun’ (Rose, age 72, adherer) ‘[name of ambassador] was my ambassador but then she went on holiday and then it all changed. Everybody just sort of took turns.’ (Anita, age 65, adherer) ‘They had to go off cruising or whatever they were doing. There were 3 different ambassadors in our group’ (Henry, age 69, challenged but remained)
Explore what your walkers find useful in terms of reducing their sitting (autonomy support)	‘The part where the interrupted sitting, I found quite interesting because a chiropractor had said to me before you said it that you shouldn’t sit any longer than half an hour. He actually said, when you’re sitting watching a TV programme at night, it’s very easy’ (Enid, age 86, adherer)
Explore what your walkers find useful in terms of keeping up their walking (autonomy support and autonomous motivation)		Self-monitoring of behaviour – pedometer ‘I still use it. As a matter of fact, I’ve got it on right now and it was a matter of great interest as to how many steps I’d done in one day and I try to increase them if I could’ (Elizabeth, age 87, adherer) Personal challenge promoted sustained motivation ‘Keeping it ongoing was a challenge in itself because that’s what I do. I said, ‘Okay, I’m going to do it, so I’ve got to do it,’ and no matter what else comes up, you try’ (Anita, age 65, adherer)	Self-determined motivation ‘There was a group that did enjoy walking, that still keep going’ (Anna, age 74, ambassador completer)
Explore what will help your walkers to continue their walking pattern after week 10 (autonomous motivation)			Self-monitoring (general) ‘The other thing you might be interested is that I’m now using the apps on my phone too so that I keep counting steps’ (Henry, age 69, challenged but remained) Social support ‘I felt on the whole our group was very successful. We seem to have no trouble of meeting and we didn’t usually tell people why we wouldn’t be there, but I think we’re going to keep the group going’ (Enid, age 86, adherer) ‘Try and keep it going but open it up to other people in the village’ (Beatrice, age 76, adherer) Personal drive to continue ‘Even though I’ve finished the 16 weeks I’m just going to keep going for myself, walking bigger dogs’ (Anita, age 65, adherer)
Celebrate success, discuss which changes your walkers have noticed as a result of the programme, and setting new goals (competence support)			Walking programme as a catalyst for new PA behaviours ‘I must admit that since we did that group walk, the group and quite a few of those people do the circuit training group twice a week’ (Anna, age 74, ambassador completer)