I just read a great book called Get on Board by Jim Haskins. It was very interesting and I was endlessly surprised by Harriet Tubman and the other "conductors'" bravery. What was really amazing is was that Harriet Tubman went into the "Deep South" disguised as a tradesman and spirited off a few slaves in the night, transporting many of them all the way to Canada, and with a debilitating illness too! This really impressed me and showed me Harriet Tubman really wanted freedom for all people. She owned a gun, not to use, but to frighten her passengers into staying with her and not running back to their plantations, which was obviously a big issue.
However, Harriet Tubman was not the only "conductor" on the Underground Railroad. Another notable one was Frederick Douglass, (both Douglass and Tubman were former slaves, whose names were generally given by their masters) who, when he found freedom, learned how to write and wrote a book about his life. He then began multiple trips back to the South to escort other slaves to the North or even Canada. Quite possibly, these notable abolitionists were inspired by their own experience of the hardships and just plain wrongness of slavery, and of how to escape it.