1) You can have too much of a good thing. 

2) Why then, can one desire too much of a good thing? William Shakespeare 

3) Never too much of a good thing.

4) This is surely too much of a good thing.

5) That's too much of a good thing.

6) But you can have too much of a good thing.

7) Example : Enjoy it! You can't have too much of a good thing.

8) I will remember them as living proof that you can have too much of a good thing.

9) Sunlight may be the best disinfectant, but there can be too much of a good thing.