It is impressive that Tiller did not mentally buckle under the 18 years of death threats he received. He was already shot in both arms during a murder attempt sixteen years ago. His name was found fifteen years ago on an assassination list. He fortified his clinic with bulletproof class, and traveled with a bodyguard.
The story of his earlier life is also poignant (article):
... his path was altered by a 1970 plane crash that killed his father, mother, sister and brother-in-law.
The former Navy flight surgeon was left with his father's family practice in Wichita, and he soon learned a secret. One of his father's patients asked him whether he, like his father, would perform abortions.
At first, Tiller said, he did not believe his father had risked his medical license by performing then-illegal abortions. But after the Supreme Court's landmark Roe v. Wade decision legalizing abortions in 1973, Tiller began providing them.