Aside from running, most people I know who are into fitness are doing HIIT (High-Intensity Interval Training) or Crossfit. HIIT is mainly a cardiovascular exercise while Crossfit is a combination of cardiovascular exercise and strength development. These types of exercises provide short but intense workouts. Maybe these are just trends just like those diet fads, but they are popular these days especially to health buffs because it works.
Another reason why most people are shifting to Crossfit is because it only needs 30 minutes to 1 hour of workout unlike going to the gym which will take you more than hour to finish. Gym memberships are expensive too, with Crossfit, some routines can be done on your own without those expensive machines.