Just get good at paying attention to bodily sensations. It might help to actually try saying things out loud, or writing them down, just going through a list of everything you notice about how your body feels right now. What you will tend to notice over time is that there are certain characteristic familiar patterns of how you are feeling.
When boys are showing care and concern and support for other people, celebrate it in the same way that you might celebrate more traditional things that are celebrated for boys, like sports victories or catching a big fish. You want to celebrate when they care for friends or family, too