Since ancient times, it's been known that our thoughts create our lives. Siddhartha (the Buddha) said "We are shaped by our thoughts; we become what we think. When the mind is pure, joy follows like a shadow that never leaves."
Henry Ford is quoted as saying "If you think you can do a thing or think you can't do a thing, you're right."
The thoughts you dwell upon, that you come to believe, become what we call a self-fulfilling prophesy. That is, you make your beliefs come true. Whether you intend to or not. Whether your thoughts are right or not.
For example, in 1966, researchers Rosenthal and Jacobson did a study in which they told elementary school teachers that groups of children were very bright -- in the top 20% of their classes. The children were actually just randomly selected, but the teachers treated them a bit differently than other students. Favored them. It was very subtle. The teachers were not even aware they were doing it. As a result, the students' year-end test results showed a greater improvement than the non-favored control group. It came to be called the Pygmalion Effect.
So, you can see that what you think and believe, affects your behavior and choices and influences the behavior of people around you.
If you spend time filling your mind with positive, affirmative thoughts, you'll not only feel better from thinking better thoughts, but also act in positive ways. That will cause others to respond to you in more positive ways. When the positivity comes full-circle, you'll have your good thoughts and feelings confirmed. And a new "positivity loop" will begin.
All of that means that you can collect motivational and inspirational quotes from wise thinkers both modern and ancient to memorize and meditate upon. To create positive thinking, feeling and belief. To change any harmful belief system. To start an endless feedback loop of positive growth and self-renewal.
The simplest way to start collecting motivational and inspiration quotes is to simply Google "motivational quotes" and "inspirational quotes." You'll find more sites filled with such quotes than you'll know what to do with.
Most motivational or inspirational quotes are from people who've been successful in work, love and life. They have practical value for you in all those areas. Just as you would create a positive environment by having successful, upbeat people around you, you create such an environment by surrounding yourself with their best thoughts.
Just cut and paste the quotes you find most meaningful and helpful into a text document. Keep it on your computer or in the cloud. Print the best of the best and keep the printouts on your desktop, by your mirror, or framed on the wall. Grow the lists of quotes as needed. Pick a new special quote daily to reflect upon and keep in your thoughts.
Before you know it, you'll be thinking and living in a motivated and inspired way. Others around you will be happier in your company. Your friends will be more supportive -- and maybe even inspired to make some changes of their own.
This method has been used to change lives for millennia. Many have chosen to limit their readings to religious thoughts and sacred texts. (In fact, historic conversions to better beliefs and behavior have come from that method.) However, most of us lead secular lives and find a wider selection of wisdom and philosophy more useful. Either ways works.