Sales — and for that matter, any customer-facing role — is kind of similar. Delusion might be too strong a word, but successful salespeople need to be more self-confident than your Average Joe. You deal with rejection day in and day out, so you need to have a thicker-than-average skin if you’re going to keep coming in every day.

It’s hard to keep your confidence levels high, though. If you’re having one rough day after another, how do you keep your energy up and start every day fresh?

Lucky for you, science is on your side. Try the list of exercises below you can use to “hack” your own psychology and give yourself a boost of self-confidence when you need it.

1) Do a “power pose.”

Amy Cuddy’s TED talk “Your body language shapes who you are” is a must-watch for all salespeople. In her talk, Cuddy, a social psychologist and professor at Harvard Business School, reveals that your body language can change how you perceive yourself.

Cuddy conducted a study where subjects were asked to stand in high- and low-power poses. Their levels of testosterone and cortisol, hormones that influence confidence and stress levels, were measured before and after they did so.

The group that assumed high-power poses saw a 20% increase in testosterone and a 25% decrease in cortisol after standing in their pose for just two minutes.

That means your body language can literally hack your brain. Here are five high-power poses to try out the next time you need a boost:

1. Lean back in your chair with your feet up on a table, hands folded behind your head
2. Stand up and lean over slightly, with both hands resting on a table surface
3. Stand with your legs apart and hands on your hips
4. Lean back in your chair with one ankle crossed over your other knee, hands folded behind your head
5. Lean back in your chair with your legs apart, and drape your arm over a chair / rest next to you

2) Smile.

Smiling is a powerful mode of communication. Humans can identify different smiles even if they’re just listening to audio, and we can distinguish between genuine and fake smiles as well.

But even a forced or fake smile is good for you, according to the 2012 Psychological Science study “Grin and Bear It.” In the study, researchers placed chopsticks in subjects’ mouths to produce a Duchenne (genuine) smile, standard smile, or neutral expression. The subjects in both smile groups had lower heart rates and were less stressed.

So even if you’re not feeling it, smile — it’ll make you feel better.

3) Have a “confidence buddy.”

When you’re feeling down, it can help to lean on your friends and family — after all, it’s nice to know that people are there for you.

But science suggests that social support can have positive long-term effects as well. According to Psychology Today, having a support network helps people manage their stress and boost their self-esteem. A 2013 study even showed that shy people have lower self-esteem than people who are more outgoing.

Whether it’s a work colleague or a particularly responsive friend, ask someone to be your “confidence buddy.” When you need a boost, let them know you need their support — and of course, do the same for them.

4) Listen to a high-power song.

It’s well-known that music can affect your productivity and energy levels. But according to a 2014 study in Social Psychological and Personality Science, it can affect your confidence as well.

The researchers tested 31 songs from multiple genres to see how powerful subjects felt before and after listening to clips. Within the high-power list — which includes songs like Queen’s “We Will Rock You” and 2 Unlimited’s stadium classic “Get Ready For This” — they found that music with heavy bass made listeners feel more powerfulmade listeners feel more powerful thansongs with low bass levels.

The takeaway? Queue up a playlist of your favorite bass-heavy songs the next time you’re feeling under the weather.

5)Take on an alter-ego.

If you watch Silicon Valley, you might remember a recent scene in which quiet, reserved Jared adopts the alter ego of “Ed Chambers,” who is loud and assertive. As “Ed,” Jared gets everything he asks for.

According to a study published in the American Sociological Association’s Social Psychology Quarterly, Mixed Martial Arts fighters use this same technique.They boost their confidence and stamina by giving themselves as powerful alter egos in the ring.

To apply this strategy, imagine you’re someone else on your next call. Maybe that’s a top-performing rep on your team, or a character you’ve invented yourself. Think, “What would [name] do in this situation? What would they say?”

This doesn’t mean you should always act like someone else. Successful salespeople develop their own unique selling style and stick to it. However, when you need a quick boost of confidence, getting out of your own head can make a big difference.