Personally the biggest challenge I see is making sure that my diet is in order. Meal prepping for me is key on training days and best of all, this benefits my family when we all have an easy meal prepared. I'm fortunate to have a dietitian as a wife to guide me into better choices, but I focus my efforts the most on days I want to train. Pacing certainly helps too. If you physical conditioning isn't quite where you want it or it should be, controlling the pace can remove that challenge. For some, pacing might mean know when to take a round off.
Studying quality videos, taking notes, and visualization are how I approach the mental side. Sometimes, time on the mats is hard to get, but with the trio of activities I mentioned I feel I'm able to get more out of a training session.
Replied on How do you structure your training to...
14 Mar 14:18
Thomas Rozdzynski eating foods that you can pronounce what's in it is my biggest suggestion.
There is so much more to expand upon, but the above will help with getting you on the right path.
Also do be afraid to do your own experiments. Sometimes too aging will play a role. You might have been able to eat something pre-training 10 years ago that doesn't work now. If you can't figure it out, find yourself a professional to help cut down on wasted time.