Doesn't have to be big things. For husband and kids, picking up little things that I know they'll like, or saying i heard a song today and I remembered when we... Even just stroking their hair as I walk past or smiling when they catch my eye.
For other family and friends it might also be little gifts, or keeping an article or book that I know they'd enjoy. Getting in touch to see how their day went especially if you know there was something going on that was important to them.
People just like to know that you think about them even when you're not in the same room.