The inner workings of the human brain are still one of humanity's great mysteries.

In fact, Steve Jobs famously trained his brain using Zen mindfulness meditation to reduce stress, enhance clarity, and boost his creativity.

What if you could actually train your brain to be smarter?

A recent Quora thread posed the question: What are some of the easy things that people can do to keep improving their intelligence?

Over 100 professionals weighed in with their favorite tactics for making themselves smarter--easy to practice habits they work into their daily routine. Business Insider columnist Skye Gould then took those suggestions and created the infographic below.

You probably have "Things to Do" lists. I know I usually have one going on my desk. But have you ever made an "I Did" list, itemizing your daily accomplishments? It's a different way of framing the tasks you achieve each day, and it can actually help make you smarter.

Writing down what you learn is another tactic that only takes a few minutes, but it can help you better retain information and reinforce what you've taken away from a meeting, conference, structured lesson, etc.

Some of the suggestions are more fun, like "Use a word-of-the-day app." This is a noncommittal way of building your vocabulary, and becoming smarter, in just the few seconds it takes you to check the app.

Each of the ideas below is designed to enhance your intelligence. Although no one tactic will send your IQ through the roof, combined they can help you stay sharp and even become smarter, one day at a time.