Great topic, one of my big interests.
If you don't have energy for long runs it is probably either that you are not keto adapted, or that you don't eat enough protein. If you are keto adapted and eat enough protein your muscle glycogen will be similar and the respiratory quotient (how much fat vs carbs you are burning) will be improved. This should lead to enhanced endurance.
See e.g. the faster study: https://www.sciencedirect.com/science/article/pii/S0026049515003340
Anything other than the american standard diet is an improvement. The body cannot handle large amounts of carbs and fat at the same time.
You can either select a high carb diet (mostly plant based) or a low carb diet (usually more animal based). People have found success with both approaches.
Personally I find it very difficult to get all micro nutrient on a plant based diet and my stomach cannot really handle too much plants. I also like the animal foods more so my approach is low carb with 95% animal products (carnivorish). I don't think it is a good idea with strict keto because you don't get enough protein to handle hard physical activities. When you eat low carb with high protein you will go in and out of ketosis, which is enough to get the benefits from ketones.