When I “didn’t believe” in God, and hated everything about the “God concept,” I started silently asking for help in the morning, and saying thank you at night. I had no belief, or faith, or anything other than a semi-open, but still mostly closed, mind. Over time, it became the most important part of my life. Prayer is something that can only be understood through the act. If you want to try it, do it every day for 2-3 weeks. You can make the prayers longer if you want to, or do a pre-written prayer, like the Saint Francis Prayer. Worst case scenario you’re just talking to a wall. See what happens.
