I am aware of how nuts this sounds coming from me. I'm supposed to be a motivational guy who encourages you to give "110 percent" every time – you know, the "Biggest Loser"-style cum Facebook WOD approach to working out. But in the age of CrossFit and other high-intensity regimens, and the enduring age of all-or-none exercise commitments, I encourage to never give it your all when training. Stop. Read that again. Because I, in fact, encourage you to never give more than 90 percent.

Here's why:

1. Injury

I remember always being asked if I was "maxing out today" when my friends and I bench pressed in my formative years. (Duh, of course I'm maxing out ... I'm a man!) Oh, the folly of my ways. Not only did this lead to some of the ugliest reps, thereby reinforcing even uglier "form," if you can even call it that, but it led to shoulders that would always hurt. Shocking that terrible form with the heaviest weight I could manage on a frequent basis would do this, I know.

In later years, as I realized there was more to strength training than chest and bi's (bro), I started aggressively chasing my deadlift numbers. While I didn't try to achieve a maximal lift every time I worked my deadlift, I was always working at 90 percent and above. This slowly took its toll, as my numbers did start to shoot up ... just as my form started breaking down. And it wasn't just my form; it was my body. I had my first real back spasm as a result and ended up crawling around for a week – literally.

Whether it's a shoulder, back, knee or any other body part, bottom line is: If you're injured, it's very hard, if not impossible, to train. If you are not training, you are not progressing.

Herein lies the key, and I assure you it can be a very fine balance, of working just hard enough to get better, but not to the point of breeding faulty movement patterns, dysfunction and injury. This encompasses both art and science, and why most folks who exercise at all would benefit from at least consulting with a qualified trainer for at least a few sessions.

There have been a number of folks in the strength community who have evangelized this notion, including legendary bodybuilder Lee Haney, with his "stimulate, don't annihilate" mantra, and renowned strength and conditioning coach (and beast) Jim Wendler, with his 90 percent training max approach, as detailed in his 5/3/1 program. By simply embracing stimulating muscle and strength gains, without the risk of going 100 percent all of the time, you will avoid injury and keep progress coming for the long haul.

2. Habit forming

We've all heard it (or said it): "Starting tomorrow, I'm going to the gym twice per day, every day, for at least an hour." Most New Year's Resolutions take on this form, and we all know how well that works; we're lucky if it last until January 2. Even beyond January, many fitness goals take on this form. Unfortunately, it's just not the way habits are formed.

While the cessation of negative behaviors does seem to work like this quite often (e.g. "I am never smoking again"), building positive behaviors doesn't. In fact, when building positive behaviors, less is more. So much so that Prof. BJ Fogg, an expert in the formation of positive behaviors, would likely argue that simply strapping on sneakers a few times per week will foster a regular gym habit more reliably than actually forcing yourself into going to the gym for daily workouts. (If you haven't checked out his Tiny Habits course, I would highly suggest doing so.)

I won't get in depth about the broad topic of habit formation here, but suffice it to say, in the gym, less is certainly more. I can't tell you how many times I have encountered a nascent exerciser who was crushed by an over-eager (if not sadistic) trainer and now doubts his/her ability to do anything worthwhile in the gym if that is what it takes to get in shape.

I encourage the opposite. Exercise will never become a habit if it's painful or even too uncomfortable – physically or psychologically. If you are trying to form a new exercise habit, I suggest always leave yourself wanting more. Think you'll jog for 20 minutes on the treadmill? Do 10. Lift weights for an hour? Stop at 30 minutes. (Note that this is my suggestion for folks who are trying to form a new exercise routine, not for those who already have one.)

By leaving yourself knowing you could have done more, and maybe even wanting to do more, you won't risk overdoing it, and you'll leave yourself physically and mentally fresh to cultivate this new habit. If you've ever failed before with an all-or-none approach, please try this!

3. Mental burnout

The first two items here, whether you're a seasoned iron vet or someone just getting started come with psychological warnings as well, as I briefly touched on above.

While folks who have been working out longer will likely be less susceptible to mental burnout than those just starting, they are not immune. Constantly pushing the accelerator and going after it 100 percent will inevitably lead not just to physical burnout and possibly injury, but it comes with a mental toll as well. Heck, I've been there more often than I'd care to admit. I had those days (that turned into weeks) where I just didn't feel like training at all. And instead of listening to my instinct, I pushed through anyway. Some of these times I advanced my training, but more often than not I missed lifts or even injured myself. If your mind isn't there, you can't count on your body to be there.

And if you're brand new, don't you already have a hard enough physical mountain to climb? (Pardon the pun!) It's quite enough that exercise might be uncomfortable, but even if you've already pushed past the total newbie phase, and now fantasize about doing more, and more and more – which is great – there will be an inevitable point where this wears off and you wonder why you ever got started in the first place. The easiest way to stay ahead of this is to always leave yourself wanting just a bit more; always leaving "a few reps in the can;" always knowing you could have handled another 10 pounds on the bar.

And for the doubters....