> Go to a good shoe store that caters to runners

I did that and I even paid extra for the "running assessment" that they were offering to those interested in running the Berlin marathon. It took me ca. 4 years to recover from the damage those shoes did to my knees.

I would say "go to a doctor", but the first one I visited just googled "running shoes" on his computer and told me to get something like that. At least the second one actually knew what he was doing.

My point being: I would suggest everyone to try really hard to get a good recommendation instead of trusting someone blindly.