Despite following a command to pay taxes and pay off debts to others (Romans 13:6-7), Paul is not primarily concerned with money here. When Christ died on the cross for our sins, He paid the price for our sins in full. He shows us through His life, death, and resurrection what love is. We are permanently in debt to Christ for the lavish love and grace He has poured out on us. The only way we can even begin to repay this debt is by showing the same kind of lavish love and grace to others. 
We live in a world filled with envy, comparison, and jealousy. We tend to focus more on how we can use others to our advantage than on how we can help others. We try to earn more money not because we want to make this world a better place but because we want to surpass our neighbors and friends. Love, empathy, and compassion have disappeared.
Do you have some additional time, and is your friend having an especially hard week? Offer to babysit their kids or drop off some dinner. All of us tend to get busy and pray general obligatory prayers. Every day, set aside some time for focused, purposeful prayer. Pray fervently and effectively for the specific circumstances faced by your family, friends, and enemies, too.

Dear Heavenly Father, loving others is so much easier said than done. Some people are ungrateful, unkind, and will not return any loving gesture. Help me to love them, as how You love me. Remind me that I never earned the love that you bestowed to me, yet You flood my life with it regardless. I pray that You will help me forgive those who have hurt or harmed me, and help me love others freely, without the expectation of anything in return. 
In Jesus’s name I pray. Amen.