Everyone is talking about the "great lock-in"

January isn’t the only time for new year’s resolutions anymore. The end of the year is having a moment too - as part of the great lock-in trend. There’s lots of content online about locking in for the last four months of the year - whether that’s working out more regularly, spending less time on your phone, or trying to get that promotion at work. Some people call it a winter arc, a September reset or the fresh-start effect - why have so many of us decided this is the perfect time for self-improvement? And is striving for optimisation all the time necessarily a good thing?We hear from Adeja Shivonne, a lifestyle content creator based in New York City, who shares how her great lock-in is going. And BBC journalist Melissa Hogenboom explains what the science says about how to successfully set new goals - and stick to them.