Just to chime in here. try to play without arching your wrist, and don't do anything that causes pain, it can lead to serious issues in the future!

But like Jeffo said, it takes practice to build the muscle memory. It takes a lot of time to get the basic foundations down. Be patient, it'll work out. Just keep in mind, if it's painful, stop doing it, and try holding the guitar with your wrist straight. This may be challenging at first and you might feel that your fingers aren't reaching far enough, but if you practice this way, which is the right way, you'll eventually get the hang of it.

- Billy