How do you exercise in this cold weather?

It's way too cold to run outside and I tried joining a gym but it didn't work out for me. I ran a marathon 2 years back and a half marathon last year. But I just changed jobs with a super long commute so I leave home by 6:45am and reach home only by 8pm. I'm exhausted by the time I reach home and barely able to cook clean and straight away go to sleep. Can someone suggest an easy way to fit exercise into my now crazy schedule. I have noticed I'm slowing piling on weight and it saddens me further. Sadly I can't move closer to work.