Replying to Cold protection for phone

Sup NS, so I was wondering if anyone had any ingenious ways of preventing their phone from falling victim to cold temperatures, other than by keeping it in your jacket. I'm sure just about everyone has experienced pulling their phone out of their jacket on the lift, putting it back in your jacket, only to have it die. So my question is, does anyone have any methods they use to keep their phone at a warmer temp? I've used a bulky glove and that seemed to work, just looking for something sleeker.