I can’t recommend pilates highly enough, but I wouldn’t try and learn via videos on Youtube as it’s a lot more complex that it looks. It’s amazing how often I think I’m doing it right before the instructor comes over, tells me to adjust something, and then it suddenly gets a lot more difficult!
Even after only 10 sessions I have a lot more mobility in my hips and less discomfort when at the gym (especially squats). The core strength and posture will be good for cycling too, although I’ve not noticed the benefit of that yet.