Table 2 Questionnaire items^a per secondary outcome including item references

 Reflective

I compare different types of fruit and vegetables before I buy something

[81]

I put fruit and vegetables on my shopping list in advance

I think carefully about what fruits and vegetables I will buy

I make a thoughtful choice for the fruit and vegetables that I buy

I choose my vegetables and fruit attentively

 Habitual

Buying fruit and vegetables is part of my routine

[82, 83]

I always buy the same fruit and vegetables

I buy fruit and vegetables on autopilot mode

Buying fruit and vegetables is typically something for me

Buying fruit and vegetables is something I do by default

 Impulsive

I buy fruit and vegetables if I feel like it

[81, 84, 85]

I buy fruit and vegetables spontaneously

I buy fruit and vegetables on a whim

I buy fruit and vegetables if it comes to mind

I buy fruit and vegetables when I see a special offer

 Health goals

I think it’s important to eat healthy

[86, 87]

 Healthy shopping

Healthy products are available in my supermarket

[88, 89]

In my supermarket it is easy to do healthy shopping

 Perceived social norm

Others in my supermarket buy healthy products

[90]

My friends and family eat healthy

 Attractiveness healthy foods

Healthy products are tasty

[91]

 Self-monitoring

In the last four weeks I have kept in my mind whether I have …

[92]

… walked long enough

… walked often enough

… took sufficient steps by going walking

 Planning

In the last four weeks I knew before I went walking …

[93]

… where I went for a walk,

… why I went for a walk

… when I went for a walk

… how long I went for a walk

… who I went for a walk with

 Social comparison

When thinking about people who are similar to you, do you think you walk less or more per day than those people? (much less than others-much more than others)

[94]

How often do you compare your own walking behaviour with that of people who are similar to you (always – never)

 Self-efficacy

How certain are you at the moment that you could meet your daily walking goal even if … (not sure at all-very sure)

[95, 96]

… I am tired

… I have a bad mood

… I have very little time available

…I am on vacation

… it is raining outside

 Intention

I intend to meet my daily walking goal every day of the week (yes, definitely – no, definitely not)

I am sure I will meet my daily walking goal every day of the week (yes, definitely – no, definitely not)

I plan to meet my daily walking goal every day of the week (yes, definitely – no, definitely not)

How satisfied are you with your Coop supermarket in general (very unsatisfied-very satisfied)

To what extent are you satisfied with... (very unsatisfied-very satisfied)

…the supermarket environment and atmosphere?

…the supermarket layout and routing?

...the supermarket tidiness?

…the assortment of food products?

…the general product prices?

...the product discount prices?

…the fruit and vegetable prices?

…the bread prices?

 Communication

The coaching app…

[97]

...invites me for a conversation

...is open to a conversation with me

…uses conversation style communication with me

…tries to communicate with me in a human voice

…tries to make communication interesting for me

…tries to make communication with me fun

…would admit an error to me

…treats me as a human being

How the user interface of the coaching app works is...

…easy for me to learn

…clear for me to understand

…easy for me to understand

 Technology as aid to enhance physical activity

The step counter app is...

[98]

…useful for me to keep track of my progress towards my daily walking goal

…valuable for me to keep track of my progress towards my daily walking goal

…good for me to keep progressing towards my daily walking goal

…helpful for me to meet my daily walking goal

 Nudge awareness

Have you noticed anything in the supermarket in the past 12 months? (yes/no)

[99]

If so, what have you noticed? (free text)

 Appreciation

It is nice when the supermarket suggests choices to me