Personally, I suggest you go out for morning exercise. But when it comes to air, in fact, the air is not so fresh too early. Theoretically, the air after 8: 30 -9: 00 can be regarded as fresh air. It depends on your personal hobbies.
The most important thing is to remember to do morning exercises in bed in the morning, because you completely neglect to warm up ... so if you are bigger, you will easily sprain your waist ... Good luck.