In terms of diet, pay attention to a balanced diet, need to supplement more vegetables and dietary fiber, not eat too much meat, and need to control nutrition and calories every day.
Endurance training is needed every day. After all, it's 800 meters, not just a race. You can run 800 meters once a day.
Strengthen the exercise of corresponding muscle groups and use fitness equipment or posture. Such as push-ups, sit-ups and so on.
I need to improve my self-confidence, believe in my progress and believe that I can do it. Think about the finish line when running, and don't give up.
When running, use the lateral muscles to exert strength. After exerting your strength, run slowly to maintain your strength, and finally run at full speed.