There is no exercise that is more simple than running. It is the easiest thing in the world to do.
Everybody learns how to run when they are a child. My daughter actually learned how to run before she learned to walk. She would get into the standing position and let go of the coffee table. Then she would start to lean forward. She would lean too far forward. Which meant that she was either going to have to move her feet quickly or fall. She kinda ran from the table to the chair to the wall.
The required list of equipment is very short. You just need a pair of running shoes. Unless you don't have shoes - like these kids in Kenya. But most of us would want shoes and some workout clothes. Maybe sunglasses and headphones would be nice too. All of it will easily fit in a small gym bag.
You can go for a run just about anywhere. You can run in your neighborhood or near your workplace. I really love to run when I travel because it allows me to explore the area and see amazing places. Running along the beach, or in the mountains, or on my own street are all as easily done.
Any time is also a good time to get a run in. In the morning, before work, during your lunch break, after work, after dinner, in the middle of the night. Whenever you have 30 minutes or an hour free.
So maybe this really adds up to running be very convenient. I'm sure that you will want to curse me or somebody when your legs burn and your chest is aching as your try to sprint up that last hill. So try to focus on the easy parts and don't worry about the hard stuff.