This talk was recorded at Scala Days New York, 2016. Follow along on Twitter @scaladays and on the website for more information http://scaladays.org/. Abstract: Jan's talk will give overview of the major components in a ML connected fitness system built on the Lightbend platform. Jan will then show the most exciting aspects of the Akka and Spark code: The Akka cluster and CQRS to handle the volume of users; the Spark code to compute the models for the users. Naturally, the talk will include the infrastructure code for continuous deployment and monitoring of the entire system. As usual, expect a nerve-wracking live demos! Jan closes with lessons learnt in maintaining and evolving the system, helping you avoid the typical pitfalls in Akka & Spark systems, and hopefully motivating you to "have a go" at designing and implementing similarly complex systems yourselves!