How to create a fitness app? First of all, it would be good to find comprehensive articles on the topic and recent marketing research to give you some insights and keys.
Depending on the audience you aim to involve, think about the significant functionality, what services will be offered, how the premium service will look, and what operating systems are to be used (iOS only, both iOS and Android, Linux). What monetisation ways do you envision? Do you plan the integration with the payment systems? Be ready that the integration might become a significant challenge.
Once you know what you want (the business requirements document would be the ideal result of those activities), estimate whether the development will be in-house or outsourced.
