Well I aim to be in ketosis and eventually be ketoadapted. I find it works well for me. I don't lift weights often maybe every other weekend. But I do run a lot, especially being part of our school's cross country's team. After the keto "flu" I feel like I could run for hours. I can't sprint as fast as I used to but I can run for a long duration so it pretty much makes up for it. Because you have to keep carbs low, make sure you get enough protein for your muscles and fat for energy. I really recommend reading The Art and Science of Low Carbohydrate Performance by Jeff Volek which goes over what ketosis is for athletes and help you make the best of it.