For a sports like skiing. What is the best way to mount a camera on me that is not on my head? I want it on a chest or shoulder. I know it comes with a laynard but it isn't really meant for sports, not strong enough.

Hello there nomnomnom. Good day and thank you for reaching out. Since this is a 3rd party accessory mount for your DJI Action 2. I hope that our fellow DJI members can share what chest or shoulder mount they are using and can give out the best recommendation with regards to this matter. Thank you and have a nice day.

You can adapt any gopro mount for the chest or backpack strap via the "magnetic adapter mount".

You can also use the magnetic lanyard and have a backup tether attached to the lens module. The attachment point is at the lower corner just behind the microphone.
Or you can get a frame that you can mount to gopro mounts (what gopro session came with).