Individuals can find people of need and work towards providing services to them; inviting others to work with them and inspiring them to likewise work for the improvement of social conditions.
Ps. please note that Mother Theresa was actually a controversial figure and many claim that she did not help the way she claimed to.
If one is influencial enough, one can make enough changes in societal behaviors to affect society. That can be the case even for Digital Influencers, nowadays, who can cause a serious change in behavior on their own followers. Another way that one's influence can be very beneficial to society is if it reaches high ranks of powerful institutions (in Mother Teresa's case, the catholic church) to organize altruistic works to help lower classes (although Mother Teresa's case is very controversial, the catholic church is known for building schools and giving free lessons of many different things, including language and professionalizing courses that help lower class people to be able to climb out of property with their learned skills and that power can be directed by a single influencial individual).
People can also become influencial in other ways just by achieving what many could think to be unacheavable, becoming a source of hope, and/or a role model.
In practice, Jim Crow madness racial segregation in all facilities in the states of the former confederate states of America and in some others, beginning in the (1870s)
