Honestly, any exercise you love can make you happy. If you’re looking for something new, try Pilates. It doesn’t take much time to get a complete workout, it’s great for injury prevention, building strength and flexibility, and it’s a lifelong practice, meaning you can be any age to enjoy the experience.
Mat Pilates requires no equipment other than a mat. Often an instructor will add small, inflatable balls or resistance bands but that is all you need. You learn to use your brain to identify exactly which tiny muscles you are using for each posture or series, so it keeps your mind working and engaged. A good instructor can help you modify for body type and injuries, or you can even do it at home with a video.