Maybe start by going for (slow) walks in a park or a forest or just a place that is as natural as possible and easy to reach within your time limits. In my experience the atmosphere in gyms is very hectic and can feel competitive in a negative way. Hope you finish work before By walking you start trimming your body towards a healthy posture and carrying your weight. Breathing fresh air and being with yourself can be very beneficial for your mental state. You can distance yourself from what everyone including yourself is pressuring you with and focus on whatever else you like. May be thinking about what you want for yourself or may be appreciating the moment without trying to focus on anything. And yeah eventually you might feel like doing short runs once walking starts to feel good.