You are always supposed to be humble. But there is nothing wrong with giving yourself some gratification. For a while, while practicing humility, I'd always tell myself to be humble and I'd respond with a simple, "it's not me, it's God," if they give me a compliment. When I felt myself trying to be happy in what I accomplished, I'd settle myself down. I never gave myself any credit (not the word I want to use but cannot think of a better word. I hope you get my point).
I deserve to smile and be proud too. I felt that if I were proud that I accomplished something that I am taking away from God and not walking so greatly in this humility walk. As I reflect I definitely feel some-what different now. My understanding goes a little deeper than just decreasing myself. Yes, God receives the glory but He also in turn passes some of that glory back to me. That's where my joy, excitement and happiness comes in at. From that it makes me want to keep moving forward. Kind of like a motivator.
But if I don't experience all of what God has for me, I am cutting my blessing short. It is not arrogant to feel some type of happiness. Humility is a balance. You can't be too humble and develop a low self-esteem nor can you be too arrogant.