Selling can be an emotional roller coaster—one that takes you from the high-adrenaline moments when you’re closing a big sales to the lows, when sales are slow.

So how can you stay on even keel when things are not going your way? Reading inspirational quotes on sales can help you connect to the wisdom of sellers who’ve come before you.

Here are 7 favorites that will help you regain your momentum.

1. “Our greatest weakness is giving up. The most certain way to succeed is to try one more time.” – Thomas Edison

If anyone knew the power of persistence it was entrepreneur and inventor Thomas Edison, who brought us the light bulb, the phonograph and alkaline storage batteries, among many other innovations.

Edison’s willingness to experiment and stick to his pursuits is a good template for the mindset sales people must emulate. It may take some time and iteration to figure out which pitch works best. And even if a prospect isn’t ready to buy now, the timing could be right at some point in the future. Trying again in situations where your competitors might give up—and keeping up consistent efforts—can go a long way.

2. “Approach each customer with the idea of helping him or her to solve a problem or achieve a goal, not of selling a product or service.” – Brian Tracy

Sales guru Brian Tracy was on the money when he pointed out that salespeople should be a resource for their customers. The better you get to know your prospects and customers, the more likely you will be able to identify their needs and challenges and help them find products or services that help them address them. That will make them welcome your calls.

3. “The key is not to call the decision-maker.  It’s to have the decision-maker call you.” –Jeffrey Gitomer

As sales trainer Jeffrey Gitomer points out here, sales people who truly are a resource to their customers and prospects don’t have to chase them down. They’ll build such a strong reputation that customers will flock to them due to word-of-mouth publicity. Getting to this point takes a long-term perspective, one built on knowing your niche better than your competitors and genuine helpfulness to everyone you serve.

4. “Nobody likes to be sold to, but everyone likes to buy.” – Earl Taylor

Most of us feel cornered when someone tries to talk us into something and start looking for the exits, as leadership, sales and communications skills trainer Earl Taylor pointed out. You don’t want to be the person who’s doing the cornering. Offering something that people genuinely want to buy is important—but having the right product or service at the right price is only part of the story. You also have to present it in an appealing way, one that is focused on benefits that really matter to the customer. How do you know what those benefits are? Talking with customers and doing deep listening to what they say is a good place to start.

5. “Either you run the day or the day runs you.” – Jim Rohn

To serve your customers well, you need to stay focused, as entrepreneur and motivational speaker Jim Rohn knew well. Using a time management system such as the one described in the “The Seven Habits of Highly Effective People” by Steven Covey can help you keep your attention on getting the important things done, so the days don’t blow by while you’re “putting out fires.”

6. “The secret to man’s success resides in his insight to the moods of people, and his tact in dealing with them.” – J.G. Holland

Novelist, poet and founder of Scribner’s Monthly J.G. Holland understood how important empathy for other human beings is in being a success.  Buying is often an emotional decision, so the better your instincts into how prospects and customers are feeling, the more successful you’ll be. Many sellers miss sales because they focus too much sharing on a long list of benefits a product will bring and less on how buying it will make the purchaser feel–whether that’s more secure, more energetic, younger, or smarter. If you feel you need to strengthen your skills in understanding other people, consider reading Daniel Goleman’s classic Emotional Intelligence.

7. “If you are not taking care of your customer, your competitor will.” – Bob Hooey

No matter how much your customer may like you personally, he or she won’t stick with you if you’re not delivering what you promised. Make sure you’re meeting expectations on every sale so you don’t have to worry that an upstart business in town or on the web will lure your most loyal customers away. Many businesses fall down on serving customers, so if you excel at this, you won’t need to read motivational quotes like this one from sales coach Bob Hooey. You’ll be too busy talking to customers and filling orders.