This is one of the biggest mistake people make, a lot of people assume that the more you train your body, the more you'll get out of it. WRONG! The body is a magnificent thing indeed but like all things it needs time off. If your training 7 days a week and pushing yourself to the limit, there will be no time for your body to heal, and its this healing / resting process that gives your body the time to recover, regenerate broken down tissue and therefore you'll be seeing results.
I personally had a problem with overtraining; I was looking to put on mass, and thought the best way to go about it would be to train as much as a I can! I had been doing this for a period of time, and I did not see any results, I was confused and did not know what I was doing wrong. I then went on to find out that I was overtraining and now I only train 3-4 days a week, and by doing this I saw the effects immediately
Training Like A Bodybuilder
If you're looking to get really tough and adding mass to your frame in the MMA world, training like a bodybuilder is the wrong way to go about it. You see training like a bodybuilder involves using heavy weights and these are not going to help you with your MMA at all. You will just sap all your energy and bodybuilding is not the way to go about to win fights, its skill and technique that will get you the win. There are different ways to go about adding mass to your body and specific exercises that not only will add mass to your frame but improve your endurance, flexibility, movement and a lot more.
I train at my local gym and for a long time I was training everyday like a bodybuilder, I was training in the gym 3-4 days a week, lifting weights and just trying to add mass. When it would come to my MMA class, and when it was time to do pad work or grapple, I realized that I would gas out after 30 seconds! I was on the wrong track in order for me to improve my overall fitness. I was shown the correct way, and by using the crazy 8's routine, I saw a difference within the first 2 weeks.
Not Developing a Proper Base Level of Strength
If you're looking to win fights you need a base level of strength. Its pointless in knowing in all the techniques but without that strength your not going to get far. Okay obviously endurance, flexibility all those tings matter when it comes to MMA, but you need that strength behind you for that explosive power and the ingredient to putting your opponent down.