Making new friends can feel more daunting when you're past the stages of playgrounds, school sports teams, and dorm rooms.

A whopping 58% of American adults report being lonely. Every seven years, people lose half their friends, according to one study. And the average person loses two social ties, including friends, when they get into a romantic relationship. Those with kids lose even more. 

As a psychologist and expert on human connection, I know that the people who are most successful in building and rebuilding their social circles are the ones who don't wait for new friends to come to them. They initiate and cultivate. 

Here are seven phrases to break the ice and nurture new friendships, no matter how old you are. 

1. 'I love your _____! Where did you get it?'

Striking up conversations with new people is the first step of any friendship. 

While talking to a stranger may seem nerve-racking, people are more open to conversation than you think. One study found that only 40% of people thought the first stranger they approached would be open to talking to them, and yet in reality, strangers were open to talking 92% of the time. 

Try paying someone a genuine compliment about their shoes, t-shirt, or overall style. It's sure to make them more open to talking to you. 

2. 'How do you like _____?'

People like being asked for their opinions. Sharing them activates the brain's reward centers. 

You can apply this research by using your shared surroundings to strike up a conversation with a stranger. 

If you're trying to approach another regular at the coffee shop, ask them how they're liking their drink. If you're at a new bar, ask how they feel about the music. If you're visiting a museum, ask what they think of the art. 

3. 'Do you have any recommendations for _____?'

People tend to like people who like them. Asking for recommendations sends the signal that you appreciate someone, value their opinion, and are curious to hear what they have to say. 

Try asking about a book, hobby, or movie they enjoyed recently. 

Their recommendation can inspire you to follow up next time you see them: "Oh, I listened to that podcast! Thanks again for suggesting it. I loved the episode on _____, but I have to know what you thought about ______."

4. 'It was great to meet you. I'd love to stay in touch, if you're open to it. How do you like to stay connected?'

One conversation doesn't make a friendship, but it's a start. Try to turn your initial interactions into something more. This is a great line to use at the end of a conversation with a potential new friend that shows interest without overstepping. 

While some people might be open to exchanging numbers right away, others might prefer to connect on social media first. 

Social media allows for repeated, low-stakes interactions that make some people feel more comfortable. You can get a glimpse into their lives through what they share, which can ease the transition from strangers to friends hanging out.

5. 'I've enjoyed getting to know you. Let's make plans to hang out more often'

Friendship is built on repeated interactions and shared vulnerability, according to sociologist Rebecca G. Adams. 

After you've had one or more small, unplanned interactions with someone, you can add some vulnerability by expressing appreciation for the connection you already have, and then asking to make plans to hang out again — on purpose!

People tend to be particularly open to building a connection when some sort of foundation is already in place. 

6. '_____ made me think of you. I've been meaning to reach out. How have you been?'

One way to pursue a new friendship is by reigniting an old one. Most people lose friends not because there were insurmountable incompatibilities, but because life got busy. 

People tend to underestimate just how much others appreciate hearing from friends out of the blue. When people reach out to old ties, they also have a higher level of trust with them than they do with current acquaintances. 

So if you notice a knickknack or hear a song that reminds of an inside joke with a college housemate, send them a message. Sometimes reminiscing about a pleasant memory is all you need to reconnect. 

7. 'I'm always looking for new friends to try/do [a particular activity]. Would you be interested?'

People decide how much to invest in a romantic relationship based on how likely they think they are to get rejected, according to a popular theory. The same is often true with friendships. 

By mentioning specific activities you'd be interested in doing, you can gauge whether or not you'd get rejected if you invited someone to join you in the future. You're also letting people know you won't reject them if they reach out about these events or hobbies. 

When you do something exciting or unusual with an acquaintance, research has found, you feel closer to them. So go ahead and tell prospective friends you're looking to join a fantasy book club, go to a goat yoga class, or try glass blowing. 

Marisa G. Franco is a psychologist, professor at The University of Maryland, and the New York Times bestselling author of "Platonic: How The Science of Attachment Can Help You Make — and Keep — Friends." Her work has been featured in Psychology Today, The New York Times, The Telegraph and Vice.

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