Can anyone help me to deal with oppression?

When I was in college, I dreamed to be an ambassador. I studied hard with a high determination. Later, when I was a senior in my university, I volunteered myself in an organization which helps poor students. Later on I became a full time staff in that organization. I was so in love with this kind of help for my fellow Cambodians. However, for the past few years, I feel so exhausted mentally and emotionally. Would you love to give me some advice on this matter?