When I first got into Buddhism and meditation, one of the first books I read was The Art of Happiness, by the 14th Dalai Lama and Howard Cutler. The book is written for a lay, non-Buddhist audience. I found it useful because, when I read it, I was a non-Buddhist. That was years ago.
One common type of Buddhist meditation is called metta. You pay attention to how much you love your immediate family and pets. Then you extend that circle to your friends. Then your acquaintances. Eventually you extend the circle to your enemies and all other sentient beings.
The teacher at my zendo discussed metta in our introduction to Buddhism class. A non-Buddhist attendee asked how it was possible to extend such lovingkindness to [unpopular Republican politician]. Then the teacher responded by saying that he had the exact same problem. To me, the entire exchange was alien.
A lot of people extend compassion only to people who are "good", or who are victims. That's not how universal love works. Universal love is universal. It's not about merit. It's not about fairness.
I think universal love arrives at the same place as the Christian concept of forgiveness. You know how a parent's love for their child ought to be unconditional? Well, if we're all God's children then it's only natural for God to love humanity in the same way.
$$\textrm{Christian universal forgiveness}=\textrm{Buddhist universal lovingkindness}$$I like universal love because practicing it makes me happy. Last weekend I got to provide first aid[1] to an unconscious lady who crashed her bicycle. This week I got to help out another person in need.
If you do samatha meditation, you can basically generate pleasure on demand. I used to be confused by this. Why don't samatha meditators meditate all day long? Last weekend, while saturated with the natural happiness I got from helping people, I noticed that, after a certain point, happiness isn't really necessary. It's sort of like having a full stomach.
This isn't to say metta can't be cranked up really high. I expect metta medators can generate much more metta than I can. It's just that I use metta the way I use bleach. I got into Buddhism because I wanted to be happy. Now that I've accomplished that objective, happiness is instrumental.
[1] This mostly just meant calling 911 and following their instructions. When I arrived, she had been unconscious for 10 minutes. Her boyfriend and a Samaritan both knew this and neither had called 911. 🤦 There was a fire station three blocks away. ↩