If 1 Corinthians 13 is the chapter that sets the bar for how we're called to love as Christians - then 1 John is the book that continues those ideas and adds a bunch more layers. It's indispensable in understanding just how much God loves us - how He loves us and what happens when we start to love one another.
Once upon a time - I really believed that if I loved others - my love came from me. If a situation or person frustrated me - I imagined that I had to muster up an extra portion of love to make sure there'd be enough. No wonder God's repeated exhortations to love felt exhausting.
Actually - to best understand chapter 4 of 1 John - we really need to go back to chapter 3. That's where this portion of the Apostle John's discussion about love begins.
Interestingly - John links loving God with listening to God. Seems like I heard my parents say something similar. John also tells us that if we're not committed to obeying God - we can fall into the trap that Cain fell into with his brother Abel: jealousy, insecurity, comparison. 1 John 3 spells out what it means to love as God loves. We're encouraged to love with more than just words and speech - but with action and truth.
Loving others is a gift, an opportunity to work with God in a way that unites our obedience with His love for humanity. It also works best for me when I am most grateful to Him for what He's done for me - and most humble before Him - because I cannot do for myself at all - what He was happy to pay so dear to do for me.