Keep a journal, and try to identify everything that give you the itch to gamble. And then try to eliminate them. If it's sports, then eliminate your TV. If it's stress, then force yourself to take long walks. You get the idea. The longer that you can distract yourself from what gives you the itch, the easier it will be for it to not cross your mind.
It's not an easy task especially if you're involvement in gambling is very deep. It's like removing your soul from your body. This is going to take a long process though. I like the itch part because you're trying to determine the root cause and provide the possible resolution to quit gambling.
When it comes to gambling, pretty much every gambler knows what the root cause is: GAMBLING. It's that we cannot get rich and the 'earn free money easy' idea is stupid and impossible. Nobody would be poor right now if it was for real. I have just spent $3 on gambling and now I regret it. Yes, just $3 but it feels like I lost all I had. Now I have stopped and I will not continue again. However, this was just for the sake of getting entertained somehow.... Looks like it didn't work.