Wow! My first thread where most everyone agrees, and my first post to ever receive a compliment, thank you Joturbo. Now, in response to your social anxiety issue holding you back, I suspect that can be reduced by picking environments that you're more comfortable with. In other words, would you do better working inside or outside? Alone or in a group? Driving around or staying put? Physical labor or not? With hundreds of thousands of volunteer jobs open worldwide, there's a huge array of choices, and I'm sure that each of us feels more competant, talented, comfortable, or interested in some jobs over others. I'm sure too that anyone, despite any social nuances, can find a workable niche. The biggest step is having a desire strong enough to actually seek out the opportunities. A google search of volunteer opportunities will reveal thousands of interesting postings worldwide. Many of the most adventurous ones are overseas and require money for travel. But there are listings too for most cities, and local churches are constantly coordinating good projects in helping struggling people. In my view, the church avenue is a prime choice because you not only serve God by helping others, but you're likely to be welcomed and accepted by the small group members of a good Christian church. And that, my friend, could lead to the volunteering effort helping you (inwardly and outwardly) as much as others.
As I grow older and wiser, I'm finally beginning to learn that the best way to manage or overcome one's own problems, worries, or perceived deficiencies is to focus on others - particularly when there are so many people around us in far worse shape than ourselves. For me, that means not being self absorbed in my own life and issues, and it means consciously thinking about and looking for opportunities to show love and little acts of kindness to others each day - like holding a door open for someone, helping a handicapped person negotiate an obstacle, giving change to a poor old begger, or paying for the small item of the person in line behind me. (Paying it forward reaps incredibly rewarding responses from strangers). So while my own formal volunteering efforts are on hold now while I travel the world full time, I look for little projects and causes each day to show love and give back. It not only feels good for the moment, but it makes me feel better about myself as a person and as a Christian. It's a win-win to be able to help yourself by helping others.
Now, here's a nice song, albeit a Christian one, to help inspire you to care for others.