For most of the 20th century, science thought it understood the brain. Researchers cleverly named particular neighborhoods of the gray organ after themselves, and with great certainty poked tiny flags into portions of tissue they thought they had figured out. But they were missing something.

One of the great findings of the late 20th century in brain research came in the late 1970s and early 80s. Scientists began to discover in fact that the brain did not settle into a nice, shapely block of concrete. Actually, it remained fairly plastic. It could change, and especially in the presence of new information and stimuli. Thus, the field of neuroplasticity was born.

Armed with this new knowledge, droves of neurobiologists, cognitive scientists, and psychologists went to work, and among their many findings is the fact that certain forces mold your brain, no matter how old you are.

4. Meditation Makes You More Mindful

Accessing a heightened state of awareness and mindfulness not only puts you at calm, centering you and offering newfound inner peace. It can alter the density of your brain’s gray matter, which is good news if you’re looking to become more empathetic, carry less stress, and excel at preserving your memory.

A 2010 study showed people who meditated for 30 minutes daily, for eight weeks, had greater gray area activity under MRI scans. A number of changes took place, particularly with regards to enlarging in subjects’ posterior cingulate cortexes, temporo-parietal junctions, and the cerebellums. People became more adept at learning, processing memory, emotion regulation, self-referential processing, and perspective-taking.

3. Exercise Boosts Brain Cell Counts

Among the raft of health benefits conferred by exercise is the fact your brain undergoes physical changes when you work out. You not only improve your working memory and release feel-good chemicals, such as endorphins and serotonin, after lifting weights or going for a run; you grow the population of neurons in your brain.

Neurons are the packets of information constantly buzzing through your brain, and having more of them generally means you’ll have faster processing power and greater ability to learn and retain new information. A 2012 study showed an interesting caveat, however. While neurogenesis (the birth of new neurons) has been shown since 1999 to boost brain power, the retention of those new neurons only takes place with “environmental enrichment” to accompany it.

In essence, if you don’t use them, you lose them. And a recent study finds the opposite is also true: If you wait long enough to exercise, you could actually lose brain cells.

2. Depression Shrinks Your Brain

Joining neurons together are spindly structures called dendrites — narrow branches that transmit information through the brain, like highways between cities. In the presence of depression, largely a chemical imbalance in the brain, these dendrites constrict. They shrink in size, bottlenecking the neurotransmitters that once allowed you to feel happy, or sad, or angry — or to feel at all.

Yale University researchers investigated this phenomenon in 2012, with a study published in the journal Nature Medicine that found critical connections in the brain were broken up when a single gene was activated triggering stress. “We show that circuits normally involved in emotion, as well as cognition, are disrupted when this single transcription factor is activated,” senior author and Yale professor Dr. Ronald Duman said in a statement.

1. Memory is Like a Muscle

Memory, scientists are increasingly finding, works more like a muscle than anything else. The more we outsource our memories to note pads, daily planners, Post-It notes, and other mindless reminders, the less we need to rely on our built-in data storage centers.

London cab drivers must use their memories so much, in fact, that just to enter the profession interviewees must take a verbal test, known as The Knowledge, where they detail, street by street, how to get from one point in the city to another. The ability is so rare, and so well-respected, that some people wait over a decade to pass the test. And according to the science, their brain size reflects that dedication.

"The hippocampus has changed its structure to accommodate their huge amount of navigating experience,” said Dr. Eleanor Maguire, of the University College London, to the BBC. Maguire was the leader of a 2000 study that unearthed the finding that cab drivers had larger hippocampi than London bus drivers.

The study provided further proof that not just sick brains can change their shape. "This is very interesting,” Maguire said, “because we now see there can be structural changes in healthy human brains” — which could be food for thought the next time you find yourself needing a change in your life. Your brain could be beckoning.