This is going to be short and easy to follow. Most people when fatigued, start doing less, stop or abandon. This is not feasible if your goal is important and you want to achieve it.
There are only one single option. Prioritize and do more instead of less ! You must decrease, transform or eliminate all unnecessary time waste. Phone time, cooking time, shower time, TV time and all time just wasted.
Do more sleep, more hydration, more eating, more stretching and more mobility and strength and conditioning. More family time. Digital waste time is often important, but people also often do food prep for 30minutes while they could throw 4 eggs, a chicken breast and a bunch of veggies into a 10euro steamer. An 8minute shower can be reduced to a 2 minute cold douche. Looking for your clothes including work and training can take up often significant minutes. It is better to prepare all in advance every single day. Shorts, t-shirt, shoes, GPS watch, water, food in the slow cooker, fruits washed for a post workout smoothie, clothing ready to put on post workout and so on.
It is not going to be true, but if you had the mentality of “I am not preparing, because I am simply ready” , you’re gonna be a lot more successful.
Training is easy. Recovering and doing the necessary side-dish work is what makes the difference. Anybody can run 100 or even 200mile weeks besides more than full time jobs and a 3 children family. Except some can do it over and over again for decades on end and others only for 3 weeks before breaking down. Time spent perfecting form instead of reading up on Covid. Time spent reinforcing core abilities, instead of simply sitting on sofa. A non-tiring balance board routine or simply wiggling on a swiss ball can trigger micro adaptations what will build up over years.
Also there are things the make you stronger when strong, but weaker when weak. Just like health. When healthy you can enhance your health by eating little raw garlic, ginger, psyllium husk, zeolit, raw ground lin-seeds. I would not recommend this to somebody with a stomach ulcer ! When strong, you can do hill sprints and bounding exercises and you’ll become even more powerful and resistant. When injured, weak, non-recovered, tired, this can break you down, send you over the edge or injure you.
Some people can afford to periodize differently. Like doing 3 runs a day instead of 2 or 1. Shorter efforts, mean more regular warming up, and drills and more cooldown, stretching and mobility. This can be an option. This will also force you to eat differently. Instead of 3 major meals, you might have 6 to 8 smaller meals. Depending on the person, genetics, current circumstances and environment this could help tremendously.
Do more from everything important and eliminate the clutter !