I am a 19 year old guy. I briskly walk for around 5 km every day, run 2.5 Kms, and do a lot of skipping. What should be my daily calorie intake? I ran a 8:45 for a 3 km when I was 16 years old but now I have to run a 5 km because I am 20 but I struggle to race 5 km what should I do?