Staying in shape is as much about mental wellbeing as it is physical. It requires will and concentration to show up at the gym after putting in a 10-hour shift, when all you want to do is plop on the sofa and watch TV.

But will is not an innate quality. There are techniques you can use to improve your concentration, such as meditation. And there are certain foods you can eat to improve your mental focus and keep yourself going after most people have given up.

Some of my favorite “brain foods” include salmon and egg yolks. But here are five foods science has shown to be of particular value for keeping you focused and ready to go.

1. Caffeine

Let’s start with the drug most Americans consume to keep them going. Millions of coffee drinkers can attest that caffeine improves their focus and gives them an afternoon jolt. That jolt is just as useful in the gym as it is in the office.

RELATED: Ask the Experts: Is Caffeine Safe for Athletes?

In addition, a study published in Nature Neuroscience suggests that caffeine can enhance “consolidation of long-term memories in humans.” The study noted that people who took caffeine pills did a better job remembering images shown to them 24 hours earlier than people who took a placebo.

But while caffeine can improve focus, be careful of its effects. Excessive caffeine consumption, which the Mayo Clinic defines as more than four cups of coffee per day, can lead to nervousness, insomnia and rapid heart beat.

2. Leafy Greens

Leafy greens contain numerous vitamins that can prevent cancer, act as antioxidants, and keep stress and depression away.

One nutrient leafy greens deliver is magnesium, which scientists have found can enhance memory. Though you could use magnesium supplements, you don’t need them if you eat a healthy diet. Magnesium is found in leafy greens, whole grains, fish and avocados. All of these foods possess health benefits beyond improving mind and memory, but that is one more reason to make them a regular part of your diet.

RELATED: The Lowdown on Kale Nutrition

3. Water

If you’ve ever been dehydrated, you may recall feeling confused, lost and unsure of your surroundings. Dehydration or even simple thirst can make you lose focus. You need water to cure that problem and get your brain back to normal. In fact, water enhances the electrical signals your brain needs to function.

It should be noted that though caffeine has its benefits, coffee and soda can make you thirstier, which can harm your focus. Drink water either before or after you have your coffee. In fact, start your day with at least one 8-ounce glass of water before you have your morning coffee. It will replenish the water you lost in your sleep, ensuring you start the day fresh.

4. Dark Chocolate

This doesn’t mean you get to pig out on Hershey bars. But dark chocolate has health benefits when consumed in moderate amounts. Chocolate contains an antioxidant called flavanols, which scientists proved in a study can help people retain their memories and boost blood flow to the brain.

If you really want to stay in shape and think eating chocolate doesn’t fit with that goal, cacao powder works as well. This is a secret even poker players, who have to endure long tournaments, implement in their game. Note that cacao powder and cocoa powder are NOT the same thing. Cocoa is roasted cacao, and the roasting process destroys key nutrients. If you want to use cacao powder, keep it raw and use it in foods such as shakes. You can even eat the powder, though that can be an acquired taste.

RELATED: Post-Holiday Chocolate Health Benefits

5. Oatmeal

We’ve all been told that we should eat a solid breakfast at the start of the day, but what are the actual health benefits of doing so?

It turns out that a nutritious breakfast can increase your strength and endurance, pick up your metabolism, and improve your memory. You may think you can dissipate that post-wake up fog with a cup of coffee and some donuts, but a good breakfast is a better option. It will give you all the energy you need to work hard and train hard for an entire day.

And when it comes to breakfast, oatmeal is one of the best foods. It is low-calorie yet filling, so you won’t feel like snacking throughout the day. And oatmeal contains magnesium, which can boost your brain and your memory.

Make sure that the oatmeal you eat has plenty of grains and fiber for the biggest health benefits.

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