Reduce the Weight of Your Backpack/Bag: We're usually texting when we're out and about, which means oftentimes we'll be carrying a backpack or bag of some sort. This doesn't help in terms of weighing you down while you strain your neck to use your phone. Try to only carry what you need with you and don't make it a habit of walking around with an overstuffed bag. After all, your phone is basically a swiss army knife of the things you need anyway - games, email, music.
Exercise: Any sort of exercise is encouraged, even if you just take a walk around the block. Whenever you're physically moving around, that's when you aren't texting or attached to your phone (or at least we hope so, as you need to see where you're going!)
Power Off: If you can, try unplugging and taking a mini vacation from your phone once in a while. You can try with a couple hours a day and extend the time if you're able to. Our phones can actually be a large cause to our stress levels because you're constantly connected to something that goes off all the time. It's the month of resolutions and this would be a good one to make.
If you want to learn more about text neck, there's an entire website dedicated to it here.