As someone who always experience this way too much before (seldom now).... here's my advice:
Don't sleep too much. Just sleep enough.
Exercise/warm up every morning. In order for us to function well, our brain needs our body to be in good condition.
Don't take too much sweets! It boosts you yeah. But it drains you a lot when it wears off.
Eat enough and healthy - if you eat a lot. Most of your energy are focused in digesting that food. Making you feel tired/restless. Hence the unproductive attitude.
Just start. You can't do things if you don't try to start. Be flexible in case of changes on your plans.
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