If I ask someone, "What do you THINK about global warming", I am asking for their opinion or VIEWPOINT.
They might answer, "In my opinion, it is a major problem".
In contrast, If someone asks, "How do you FEEL about global warming".
They might describe their emotions. They might answer, "It frightens me to read some reports".
If someone asked me, "What do you THINK is the best way to stay healthy",
I would give my viewpoint, "I AGREE with most experts who say we need regular exercise, healthy(healthful) food and a proper amount of sleep".
Hope this is some help to you.