There are a few settings to help
Optimize battery. Try google searching it. I can't recall them off hand. I have 2 exchange accounts pushing all day.
Believe it or not, I have tried googling it in the last five years ;-) I run my own computer support business, so I have tried everything possible to take care of this problem. The fact is, the phone uses a certain amount of energy, and the battery is a certain size. Those two things in combination allow for roughly 8 hours on the clock after my phone is taken off the charger With my typical usage patterns.
That usage does not include streaming video, streaming audio, or high screen brightness settings. I remain connected to Wi-Fi whenever possible, but for a good half of most days, I am not connected to Wi-Fi. I do not use Bluetooth and I have my Bluetooth disabled. I have location services on, because, hello, it's a phone. I want to be able to use the location services. If I wanted to disable half of the usefulness of the phone just to be over use it, I would've got an android phone and gotten even less battery life.
I just wish Apple, instead of making the phone 40% thinner with the last generation, would've taken advantage of that additional space and giving me at least the option of buying a larger battery. As it is, it looks like I'm Going to buy a battery case, and walk around with a much bulkier phone then I would have wanted to have.