In order for companies to effectively use customization as a design strategy, there should be understanding on what users would like to customize and why. This study explores the use of customization features of sports watch in order to assess the extent of customization, and to identify reasons for customization in this context. Survey data from 100 users of a sports watch were analyzed to understand how they use the different customization features: general preferences, functionality and appearance. The findings show that although the users vary in the use of customization, they state similar reasons for customization: control, ease-of-use, increased effectiveness, and better fit to personal preferences. The motivation to customize in this context is for the most part related to autonomy: to the sense of control the user has by having the tool to adapt the product according to own preferences, wants and needs.