Your grandfather was a Baptist missionary in India. His father was a Methodist minister. Both lived very humbly. Dad and I didn't have a relationship on any level. We didn't have common politics, interests - we didn't really talk. However, he still was one person that I respected deeply because of his honest, anonymous and generous giving to those in need. Watching him, I saw why he did things the way he did.
First - if you are giving consistently to others, you are not wrapped up in materialism and the unending pursuit of getting more stuff. Dad had a lot more opportunity to increase his wealth and our overall standard of living, but he was very content to live in a smaller home with an average car. As you are already probably putting together...I have not mastered this skill like my dad did. But I do recognize it to be a weakness. You will find - in general - that people think they deserve a lot and that the accumulation of wealth and material possessions is a measure of how deserving they are. Don't ever forget that you live in a country where we have far more than most people in the world.
Second - it feels good. It really does. If you're helping with money, sometimes the money is 'wasted' because the person who you are giving it to spends it in a way that you didn't intend for them. My thought is that this is a bit of micro-managing - you have to reflect on how you might make choices different then others (especially bad choices) and how you'd like to be judged / controlled / criticized in a similar situation. If you're giving with effort, the same thing can apply. For example, you might help someone get a job, but then they might quit a week later. Don't rationalize yourself into not helping anyone because of the bad outcomes you might observe. Dad was great at this - he understood human weakness, but helped anyways where he could.
Dad also never tooted his horn about his donations and was very private and anonymous (when he could be). My analysis was that its giving in its most pure form - giving without expecting reciprocity. I use the same philosophy.
Catherine told me about an Podcast that she thought I would like: Hidden Brain. Over Christmas I heard on old rerun on The Science of Compassion. Near the end of the podcast they talk about how we tend not to help those masses less fortunate than us: starving children in Africa, poverty in India, etc. Our brain does this trick on us: "If I help one, I'll have to help everyone - and I can't help everyone". Its a false conclusion we make to relieve ourself from the stress/pressure to solve for everyone. But...don't let your brain trick you like this. It is better to help 1 child in India than zero.