|Lake Michigan sunset,|
from Holland State Park
1 John 4:19 says: We love because he first loved us. Our reason to love God and to love others is grounded in the fact that, first, God loved us. Being-loved by God is the reason to love others. This "first love" is the river from which flow the streams of "other-love." Apart from this, I don't know what sense the idea of loving others makes.
A main way to experience ongoing "first love" and thereby grow the spiritual fruit of other-love is engaging in a life of prayer, a life of actually praying. Henri Nouwen writes: "Prayer means entering into communion with the One who loved us before we could love. It is this "first" (1 John 4:19) that is revealed to us in prayer." (Nouwen, The Only Necessary Thing: Living a Prayerful Life, 66)
I know from 35 years of prayer experience that these two things grow in me as I pray: 1) the sense of being-loved by God; and 2) greater compassion for others, to include (amazingly, to me) actual compassion for those who are enemies and hate me.