Yes, consistency is key. No different than saying building running endurance or increase the amount you can lift.

Quite a bit I would say. I’ve been working a desk for 20+ years and have no problem riding aggressive bikes and doing all sorts of other functional movements. The key is to be consistent and intentional with what you are doing.

Yoga or Piliates or both

I'm 54, started doing yoga 3-4 times a week about a year ago. My flexibility has improved a lot. I was never very flexible, and I'll never be able to mermaid, for example, but it has definitely improved.

Check out relax into stretch by Pavel Tsatouline

Tons! I have let my flexibility go several times and after a few weeks of training consistently in always get it back and can still improve.

Do yoga 3x a week for a month OP. You will see a huge difference!

I’m 48, always have been inflexible, and I don’t think I ever improve. But it does feel good to stretch and do barre whenever I can.

It ain’t nothing but a heartbreak

Great potential! It just takes focus and consistency. Try a beginners yoga class, or a dance class, to help you get started.

A lot. I recently started working on my turnout each day, two or three times a day, and am already seeing progress. I stretch (touch toes) each time I use the microwave oven and can get all five fingers on the ground. Now working on getting my palms flat. Am 46.

I’m in PT to help with hip flexibility and I’ve had good progress, I’m 52.

I’d say yes based on my limited experience but I do hip opening exercises every day for 30 minutes for 5 weeks.

I'm 35. I used to do gymnastics and was very flexible, but then when I got really into long distance running, i lost a lot of flexibility. There was a sweet spot era, in my early 20s, when had both flexibility and endurance - I remember being able to do a full lotus position and almost a splits.

I've retired from long distance running and have been gotten more into resistance training, swimming, and yoga. I'm wondering if yoga is similar to other activities in which you can improve over time. I'm not setting a goal to regain the flexbility of my 18-year-old gymnast self, but I'm wondering how much improvement is possible. I'd like to be able to get into a lotus position again and do more intermediate poses. I'm good with the forward folds but pretty terrible with any of the hip-opening positions like skandasana. Can inner hip and groin flexibility improve or is that something that is irrevocably lost with age?