Do you wish you would more often choose the healthy items at the breakfast buffet and ignore the pastries? Do you want to be able to stay on the treadmill for the time goal you set, even though each minute is a little harder than the last? Making healthy choices like these re­-quires willpower, the ability to ignore temporary pleasure or discomfort to pursue a longer-term goal.

Researcher Roy F. Baumeister, PhD, has found that willpower operates like a muscle. It can be strengthened, but also easily exhausted.

To better understand how your willpower “muscle” works, read this low-down from Kelly McGonigal, PhD, health psychologist and yoga/fitness instructor at Stanford University.

Increasing Willpower

According to the physiology of fitness, temporarily exhausting a muscle should lead to increased muscle size or improved ability to use fuel. The same is true for willpower.

Try controlling one thing that you aren’t used to controlling, and aim to do it every day. Like physical exercise, this act of self-control can be uncomfortable at first, but over time it is no longer a struggle. The willpower muscle has learned a new skill, and with practice, the act of self-control is less likely to deplete willpower. If all acts of willpower reflect a single strength, then training any individual act of self-control should strengthen all acts of self-control.

The Limits of Willpower

Research shows that willpower is inherently limited. No matter how physically fit we are, exerting ourselves inevitably leads to exhaustion. The same is true of inner strength: self-control depletes willpower in much the same way that exercise temporarily depletes physical power.

Because willpower is limited, each act of self-control is a win-lose effort, helping in the immediate situation but making us more likely to lose control later. Refraining from gossiping at work makes it more difficult to hit the gym after work. Resisting the impulse to splurge at your favorite store makes it more difficult to turn down dessert. This means that it’s important to set priorities and to give ourselves a break on the things that aren’t at the top of the list.

Conserving Willpower

How can you make healthy choices without depleting willpower? Margaret Moore, founder and chief executive officer of Wellcoaches® Corporation, advises planning in advance as a strategy for conserving willpower. “You don’t want to be standing in front of the fridge saying you don’t have a clue what to eat. The weakest moment of self-control is when you’re hungry and tired. Too much choice tends to overwhelm us. If you have to make a lot of choices, you’ll deplete your self-control.”

Likewise with exercise, when you’re feeling strong, set up a weekly date to meet a friend at the gym. Commit and just show up—no choice and no willpower needed.