IPhone 4 battery not lasting as long as it's meant to?

My iphone 4 is about 2 years old and recently the battery hasn't been lasting as long as it used to. It used to last all day with me using it all the time, but in the past few days i've been charging it twice a day and the battery just goes so quick even when i'm only using the txt messaging application. No other apps are running, is there any reason as to why my battery isn't lasting all day like it used to?

Have a check what apps are open in the background. Double click on the home button. And get rid of all apps that you see. Then leave it on charge over night. Should see a difference

I may be that you are over charging it past 100% before so that the battery runs out quick but takes the same amount of time to charge.

Try turning your brightness down, or make sure all of your applications are closed when you're not using them. If you've installed the new software, you'll be able to click the home button twice and your applications will show up at the bottom of the screen.hold your finger on one of these applications until the red minus sign shows up on all of them.remove all of these applications when not in use, closing the application, thus saving you both battery life and making your phone work faster.

you can also look into getting either a new phone, or a "mophie" case which doubles your phone's battery life without adding too much extra bulk on the phone itself.

I believe that battery problems are common for old iPhones. My aunt had an iPhone 3GS for almost 3 years and her iPhone has the same problem as yours. I believe that you need to get your battery replaced. In the meanwhile, try closing unused apps by going to the multitasking bar, turning the brightness down and going to airplane mode when your phone is not in use.

It probably needs to be replaced. You can prolong it by turning off bluetooth and push technology