My iPhone 4 battery dies fast. Why? What can I do to make it last longer, it drains in about 7 hours, if really in use... :/ Help!

I have the iPhone 4, the battery runs out real fast if i use it alot. I know all batteries die fast if u use it alot, but in a normal day a work I just take a glanze at the phone a few times, its not like i am constantly using it, and in about 5-7 hours it dies 😕

Me dont like that....

HELP Please... ⚠

Any suggestions on what can i do to make it last longer...