Table 2.

Findings from the focus groups and youth advisory board.

Steps in the design phase	Findings
	Focus groups	Youth advisory board
Prototype potential products	Built sample Instagram posts incorporating theoretical constructs Wrote sample text messages prompting goal setting and providing progress feedback Redeveloped website to be primarily visual and incorporate real-time data from wearable trackers Developed possible study logos and study names	N/Aa
Gather user feedback	Desire for positive media; bright colors, positive wording, and encouragement versus nagging Preference for personalized (vs generic) text messages, at most 1 per day Preference for intervention exclusively for Latinas, with the incorporation of cultural themes and Spanish phrases Preference for Chicas Fuertes study name	Largely positive response to all social media posts; appreciation for mix of cognitive and behavioral strategies for behavior change; and suggestions for even more bright colors, varied body types, and Spanish phrases Positive response to text messages, suggestions to make them shorter, and appreciation for positive language Positive response to website design and content Positive response to study name and logo Preference for cash incentives and identified prizes for engagement
Build minimum viable product	Built texting algorithm for automatic goal setting and real-time feedback based on Fitbit Wrote text messages in a casual language and positive tone Developed new Instagram posts with bright colors and with models with a broad array of body types and incorporated cultural themes and Spanish phrases Developed Instagram posting schedule of 1 post per day, which were mapped onto theoretical constructs and BCTsb Branded all study materials with the new study name and logo	Final schedule and content of text messages and social media posts developed and mapped onto behavior change theory constructs Bank of 120 Instagram posts developed featuring bright colors, motivational quotes, specific strategies for change, and Spanish phrases Website content finalized Text message algorithm finalized with positive, succinct text messages Prize and payment schedule finalized

^aN/A: not applicable.

^bBCT: behavior change technique.