I flirt too much..Any thoughts on how to stop?

I'm currently in a long-distance relationship, my boyfriend lives a couple hours away and when we're not together I find myself flirting with guys very often. I need to figure out how to stop this, it makes me feel extremely guilty because if my boyfriend knew how I was talking to some of these guys at work it would kill him. I'm a bartender and it's impossible to cut off communication with guys completely, in fact, it even helps being flirtatious at times as far as income is concerned. I need to get out of this frame of mind because I'm not being the girlfriend he deserves, I don't like doing this but I can't stop. It's easier said than done to just stop and I'm mad at myself for not being strong enough to. Any thoughts on this or am I hopeless? Sometimes I just feel like breaking up with my boyfriend for the simple reason that I don't deserve him..kills me to even say that. I feel like such a *****.