The new year is a notorious time for new things. People work themselves up over drastically changing themselves and their lifestyles, but realistically this never works. The key to a great resolution is allowing yourself time to grow accustomed to it. If you intend to change your way of life, your New Year's resolution should match that.
That being said, common resolutions people commit to are almost completely unachievable.
1. I'll go to the gym every day
Unless you can predict your schedule every single day of the year, this is impossible.
Instead, you should try to commit to going to the gym at least twice a week, or simply try and get any physical activity in. The easiest resolution to commit to would be always taking the stairs instead of the elevator.
2. No carbs in the new year
Your body is meant to process carbs, and if you cut yourself off cold turkey the next time you eat carbs you'll go hog wild. Instead, try to eat "good" carbs only. Potatoes, legumes, and so many other foods are good for you and also carbs.
In all, the number one resolution for everyone should be to be kind. Eating healthy and having a fit body is great, but feeling physically good is only half of it. Emotional stability is the most important aspect to focus on. A good way to start off this resolution would be putting good vibes into the world and they will make their way back to you.