Unless you are a doctor or engineer or you are planning to spend a year or two volunteering there is probably a fee to be paid. Perhaps you are going to build a school in the Philippines, the volunteer organization has to pay for building supplies, arrange the logistics of the program, provide homestays in the local village, create brochures and market their program. If the only objective was to build the school they would be better served hiring local craftsmen at a low cost and complete the project in a short time. The goal of the organization is more likely centered around providing a cultural experience for you and for the local volunteers and letting you see life in the Philippine village. Volunteering requires flexibility, patience, those who are self-starters, and people who genuinely respect the host people and their culture.
Volunteers never go to teach the people western ways, nor are they there to save the people.
Volunteers go to share their energy and time with the people, to experience their culture first hand and to grow themselves. Most international volunteer experiences are hosted in developing countries. Before you go you should do some research. The last thing the volunteer organization and the locals need is someone complaining about the food. You will be surprised at how much or how little you need in the way of modern comforts to be happy.