Is it mind over matter ?

In my experience, it is possible to over train. You will know when you've done it - the first 20 minutes of any work out can be hard but if after those 20 minutes you feel worse than when you started - you've over-trained!

You can maximise your work to rest ratio through planning your work outs sensibly - for example if you are doing weights you can pretty much go forever by doing a legs/core/arms rotation.

As a runner I try and do three 'quality' sessions a week - that's one pace run, one interval training session and one long run. Additionally I try and do one long bike ride and one 'other' CV session which tends to be a bike ride in the summer or bike/row/XTrainer in the gym during the winter. My 6th session is normally weights based - however when I'm doing Triathlon training I also squeeze in one or two swims a week and kill the weights completely. That leaves one day for rest and recovery....

Note that 'recovery' doesn't have to be 'do nothing' - for me, a 5K run at my half marathon pace or slower is a recovery run - it lets me stretch my legs out without tiring myself out at all. Generally any run or cycle can turn into a recovery session if I feel bad on the day - there is no point in injuring yourself or burning out by failing to listen to your body. An extreme version of this training mentality says that you don't plan how far or how long you will train for on any given day - you just set off and see how you feel. Sadly this is something my work schedule can't accommodate - but you can definitely adapt your sessions based on how you are feeling.

The thing about exercise is that it's a very individual thing. What works for some, does nothing for others and so on. I have seen people do 6 days a week of hard workouts with no problems where some people can only do 3 so it's really what your body lets you do so I agree wholeheartedly that you listen to your body and go with it. It's a huge learning process. I am very active and in decent shape, however I tried Insanity 3 days a week and running 3 days. It was a horrible combo for me and my running was pathetic. I have a friend who runs long distance, does multiple hard classes at the gym and trains for a tri without any issues so don't follow what works for others and find what works for you!

For me, the mental part is much more of a challenge than the physical part. That said, there are still limits to what the body can handle. What those limits are depend on a variety of things.

It is not mind over matter.

It is Understanding and applying training principals correctly over time so that your body adapts to a higher workload so that it can train every day and also recover properly.

It is also Applying training principals correctly every day so that the body receives enough stimulus to improve but not so much that it overtrains and stagnates progress.

My experience is that I can run every day and log 80+ miles a week now while progressing in fitness but it took a while to get there and I have screwed it up a few times in the process.

The few times my mental exuberance exceeded my physical capacity, and I acted on the urge... I regretted it. Notably, running too fast during races and running too many days per week.

I think "mind over matter" depends on the intensity and duration, and your level of fitness. Running slightly faster during a race due to adrenaline is a a good example. But ignoring the truth about physiology isn't smart... or admirable.

This might sound weird but after you work out for a while you kind of learn the language your body speaks and you can kind of FEEL when you need a day or even a WEEK off. I typically do ZERO cardio and lift 4-5 times a week. My body is fine with this but I have to schedule my workouts accordingly. For example, doing squats the day after deadlifting is a BAD idea since you use your lower back a lot during both movements. Also, if I've been out snowboarding all day I won't do my leg workout the next day since my legs are shot for a couple of days. Some days I'm so sore that I just decide that it's a good day to take off (I go more by feel and social events in my life than strictly "Wednesday is an off day" kind of mentality). Also, every three-4 months I'll do a deload week. For some people, this means lifting light weights and not lifting to failure. For me, this means not working out AT ALL for a full week. Once I come back I feel good and it doesn't hinder my progress at all.

agreed. well said.