As a runner, it sometimes seems easier just to run and not consider the rest of your muscles, but you need to strengthen other parts of your body to avoid injury and mobility/flexibility issues.
My morning routine includes stretching from top to bottom. This includes arms, back, and legs. If you’re looking for a great instructor on body mobility, I suggest you check out Jessica Valant Pilates, she is a great teacher that has a lot of freely available resources to get you started, plus, her subscription programs are reasonably priced.
Post stretching, I do 30-40 push-ups along with a few additional mat workouts. I follow the mat work with 100-120 situps on a bench (if available) or the mat.
Other exercise outside of the morning routine includes walking, when time and the weather are cooperative, and light resistance training on my home gym.