I am not an expert, but maybe something here will help. If training depletes you:
a) Are you getting enough sleep? When running track in HS & college, I needed at least 8 solid hours of sleep. When training heavily, 8 1/2 and sometimes 9 - 9 1/2 after hard days. Esp during HS growth spurts.
b) If you are meeting the above, maybe adding a 20-30 min nap midday could help make a difference.
c) Are you sleeping the same hours each night? My understanding is that studies show waking at the same time daily is important. Going to sleep at the same time is also important, unless you need more sleep -- in which case, go to sleep earlier.
d) Are you hydrating properly?
e) Are you eating properly? Getting a fully sufficient intake of complex carbs, protein, fruit, veggies, and some limited fats? Minimizing added sugar in your food? Avoiding candy and soda? Also avoiding other junk food like chips etc?
f) Drinking too much? Metabolized alcohol, IIRC, converts to sugar in your system and then to fat if the sugar-energy is unturned very soon. If I understand correctly, the body also processes alcohol like a poison, using the liver. Counterproductive to training.
g) Are you training too hard? Too many miles? Increased mileage and/or intensity too rapidly? Is the intensity of the hard sessions inappropriate? Are you running easy days too fast? Too many hard sessions? The easy-hard-easy-hard-easy-long-off approach doesn't work for everyone.
tl;dr- Training well is a lifestyle, and attention needs to be paid to all the details.