In order for you to be able to push hard during exercise, you need to have filled up the depots. We will go through how to do it in the best way.
Before exercising, it is a good idea to eat a snack about 1-2 hours before the activity.
Alternatively, eat a main meal about 2-4 hours before training.
Filling up beforehand is the basis for being able to push yourself when you exercise
On days when you exercise, you need to eat carbohydrates during the day, before exercise, to keep your glycogen stores full (so your body has enough fuel).
On days when you're not exercising, it's less important to fill up on carbohydrates. If you want to lose weight, you can cut back on carbohydrates on those days. How much you can cut back depends on how much you exercise. If you exercise at an elite level, you should never drastically cut back on carbohydrates and should eat carbohydrates even on days when you are not exercising.