One of the new features that came out with iOS 17 and iPadOS 17 was the ability to create custom Apple Fitness+ workout plans, and that feature continues to be a popular one with iOS 18. Custom workouts have been available in the Workout app since watchOS 9, but these features take it to new levels. You can now schedule monthly or weekly fitness routines, select the days of the week you plan to exercise, the planned duration of each workout, what activity type, the instructor, what music you want, and so much more.