There are a lot of good charities out there, doing work that would only be noticed if they stopped doing it.
Every year CAFOD organise two 'fast days'. A day where you go without, to give to those who don't have.
One fast day is during lent, the other during harvest. Today is the fast day for harvest. They make it really easy. All you are expected to do is miss a meal. For most this would be lunch, but depending on your circumstances you could miss breakfast or dinner. CAFOD ask that you donate what you would normally spend on one meal, and they will pass on that money to help people in a region of the world where they don't have access to the luxuries we in western civilisation take for granted.
This year CAFOD are focusing on a small village called Lushebere in DRC. You can read more about it here:
CAFOD fast day
Anyone can join in with the fast day. It's not proper fasting, you are giving up one meal. How you do that, and whether you do it properly is a matter for you. I guess you don't even need to fast if you prefer not to, just donate what you spent on a particular meal.