When we start following Jesus, we are given one command (OK, maybe two): Love God and love others. All the other stuff that Jesus and Paul and everyone else taught in the Bible comes under those two headings.
I was always taught that love is an action, not a feeling. It's actually both. But, I always associate action with significant physical action, like making dinner for someone, or giving something to someone.
I suspect some of my guilt about migraine is about my inability to "do" things, therefore "loving" other people. Hmmm, I think I just found the topic for my next counseling session . . .
But, there are ways that we can love others even in our own physical difficulties. In Romans 12, Paul gives a short paragraph on some basic principles of living a life of love. One of my favorites is verse 15: "Rejoice with those who rejoice; mourn with those who mourn."
Sometimes, the best way to love someone is to just be there, whether things are going well for them or going poorly. I don't have to be having a good day to share in the joys or sorrows of the people I love.