I think it does help to feel you're doing even the smallest thing for someone who needs you.
I completely agree. Doing things for yourself in an effort to make yourself happy only goes so far. Helping others get a task done, achieve a goal, or make some aspect of their life a little better or easier is much more satisfying than doing something that only benefits yourself.
Case in point: I've been working toward decluttering and trying to make my small condo work better for me, but with everything I do I'm left feeling like "so what?" But after helping someone inch one step closer to their fitness goals during a training session, a day of volunteering, or even accompanying an elderly neighbor with furniture shopping like I did on Saturday, my level of satisfaction at least somewhat approaches what I had when I was working.
Tell me this: why is our life satisfaction so intertwined with working?? Why can't we feel like our lives are truly worth something when we are not working???