Inevitably when you're still with no distractions, your subconscious starts surfacing various thoughts. There is a random element to what pops into your head, but there will also be patterns. Just sitting there and observing, and maybe asking yourself a few questions about what emerges, is an incredible way to become aware of your emotional state, stay grounded to your goals, and remember what truly matters to you. This exercise frequently reorders my plans for the rest of the day.
There's also value in stillness when you're in public or with other people. Just shutting up and taking in your surroundings for 30-60 seconds is kind of like a mini superpower, you start noticing little things that other people don't see. Many of the little decisions you make automatically throughout the day get better if you just, y'know, sit there and think about them quietly for 1 minute. You end up going to a better restaurant, or remembering to call a loved one, because you simply took a moment to just pause and reflect.
It's the best thing in the world really. All this mindfulness stuff has profound benefits.