Chances are, we’re all guilty of doing at least one of these five common mistakes when we step into the gym. While some seem like no-brainers, others aren’t necessarily as easy to catch – or ‘fess up to. Fix these mistakes in the gym, and you'll be well on your way to meeting every single one of your fitness goals.

1. Not Fueling Your Body

Do you find yourself tanking midway through a perfectly reasonable workout? Then odds are good that you're not eating enough or not staying properly hydrated – or both.

There's no one-size-fits-all recipe for sports nutrition, but if you can get used to the idea that food is the fuel that powers your workouts, you'll be well on your way to higher energy levels. The American College of Sports Medicine offers some great guidance to help you get your real-world nutrition dialed in. Think of keeping 50 to 60 percent of your daily caloric intake in carbohydrates, 15 to 20 percent in protein and less than 30 percent in fat.

For hydration, the ACSM recommends drinking 3 to 8 ounces of water every 15 to 20 minutes, with electrolytes added in if you're exercising for more than 60 minutes at a stretch. How well hydrated you are in everyday life will affect your workouts too, so aim to keep sipping water throughout the day so you never find yourself feeling thirsty.

2. Not Working Out Hard Enough

It happens to almost everyone at some point. You get into a great workout groove and love the results you're seeing, until one day those results just peter into nothing even though you hadn't changed a thing. Well, that's just the problem. If you don't change your workouts to keep up with your ever-increasing strength and endurance, your body will hit a plateau and stop adapting once it's used to the current situation.

Fortunately, the solution is pretty easy. Every workout contains three variables: duration, intensity and type. Change any of those variables, and your body will have to start adapting again. In other words, you'll bust right through that plateau and get back on track.

3. Peer Pressure in the Weight Room

Every gym has somebody who showboats in the weight room, flinging crazy amounts of weight around. Don't give in to the temptation to follow suit; those huge weights might be impressive, but it'll be equally impressive when said person tears a muscle or drops a weight on his or herself.

4. Not Using Enough Weight

Speaking of choosing the right amount of weight – women often fall into the trap of thinking that if they lift more than five pounds, they're going to develop outrageously bulky muscles.

Don't worry – as long as you can lift the weight at least eight times with good form, you're not going to turn into a bodybuilder overnight. What you will do is forge exactly the sort of sleek, trim muscles you see on all the fitness models in women's magazines.

5. Not Asking for a Spot

Spend enough time in the weight room, and you'll see some poor sap stuck beneath the bench press bar, unable to press it up high enough to store on the rack. Don't be that guy (but do give him a helping hand – or two).

If you're not positive you can handle the weight safely even on the last rep, ask for a spot before you start your set. Don't wait until you're in trouble to find out if there's anybody within hearing range (much less someone that's strong enough to lift the weight off you).

If you ever find yourself feeling lost in the gym, all the fixes mentioned above boil down into a few principles: stay focused, challenge yourself during every workout, stay hydrated and eat to fuel your workouts even when you're not in the gym. Do that, and you may just be blown away by how much you can achieve.

Are there any other big mistakes that you have been guilty of in the past? How have you overcome them?