Sitting in a train for hours can be a pain in the ass and on the back. Even a simple fifteen minutes yoga routine helps to maintain a good posture and relieves tension. This is what I did:

• 6 x sun salutation
• cobra pose
• child pose
• standing side stretch
• single leg forward bend
• 4 x sun salutation

The internet has more on yoga poses.

Photo by kiwinky under CC BY-NC-ND 2.0