There is a commonality with most people that come into a recovery program of being totally broken and the last thing that is probably on their mind is that they need to help someone else for a chance in their own sobriety.
Being of service comes in many different calibers with different ways to be helpful. There are tons of commitments in 12-Step programs to make the meetings run, as well as duties for the entire organization to operate. You may feel overwhelmed with thinking that you must sponsor other people in the program or become a secretary of a meeting, which is not a requirement, just something that people may feel more comfortable doing the longer they continue to stay.
Regularly attending 12-Step meetings for your recovery will give you a chance to start getting to know people and feel like you are part of the group. Participating in the meeting, even if it is only through your attendance, is being of service to the fellowship. Through suiting up and showing, you are being of service to others in the recovery community to demonstrate unity which is what 12-Step programs were founded on.
As new people come into the program much like yourself, one of the best ways to be of service is to be kind and make newcomers feel welcome during a tumultuous time in their life. What this actually does is give you a chance to stop thinking of yourself and replace that with the thoughts of helping someone else that may not be as fortunate as you. Service is what makes the recovery world go around. Since someone probably helped you when you were new, this a good opportunity for you to be of service to others.
You may not think that you are capable of being of service because you have nothing to give. If you think in that manner then you are giving yourself less of a chance to put your hand out to someone else who really needs a friend, a mentor, or an ally to help them to stay sober. The point of service is to gain more than you thought that you might have deserved by giving back what was so freely given to you.