How are we keeping our starters warm enough?

I just threw out a 2 week old starter because nothing was happening to it. I’m assuming it was because I chose to do it during the winter and my apartment was not warm enough for it. My first starter that I did a couple years ago was successful in a week but it was done during the summer. I used the exact same feeding ratio for both starters and that’s why I think this one didn’t work out due to temperature. I’ve seen other people talk about leaving the jar on a hot pad or leaving it in the oven with the light on, but am I supposed to just leave those on 24/7 because if so that doesn’t feel safe to me especially if I’m not at home. I want to see what everyone else is doing to keep their starters at ideal temperature just to get some ideas so when I do round 2 of this starter there’s a higher chance of it working.