The second sentence has a minor error where it says "I used to eat pizza" instead of "I tend to eat pizza." This error suggests that you no longer eat pizza, which contradicts the first sentence where you say you love to eat pizza. The third sentence is a bit repetitive because it uses the word "happy" twice in the same sentence. I have revised the sentence to make it more concise and less repetitive. The fourth sentence is good but it can be improved by adding "even" before "happier" to emphasize that pizza makes you feel happier than you already are. The fifth sentence is well-written and effectively conveys the positive effects that pizza has on you.

I made a few minor changes to improve the grammar and wording of the text. Instead of saying "I used to eat pizza," which implies that the person no longer eats pizza, I changed it to "I love eating pizza." Also, to make the sentence flow better, I changed "It make me more happy" to "It makes me happy." Finally, I added some additional details to the sentence to give it more depth.