Stay open-minded; stay focused. Train hard and train smart. For me, the older I get, the smarter I have to train also, because the recovery time is longer. Work on everything: become a well-rounded fighter - don't just be good at one thing; be good at everything.
Experiencing this pain in my muscles and aching and going on and on is my challenge. The last three or four reps is what makes the muscles grow. This area of pain divides a champion from someone who is not a champion. That's what most people lack, having the guts to go on and just say they'll go through the pain no matter what happens. I have no fear of fainting. I do squats until I fall over and pass out. So what? It's not going to kill me. I wake up five minutes later and I'm OK. A lot of other athletes are afraid of this. So they don't pass out. They don't go on.
The biggest way I stay motivated is to run with a group of friends. Sometimes it's hard to get going by yourself, but if you have a plan and a meeting time, you know this run will happen for sure. It's a way to have fun - while also getting in a workout. Plus it distracts from pain, helps you fight fatigue, and gives you that extra push.