Working Life is a monthly column in which Texans talk about their jobs. Thomas Polinard, who is 42, is general manager of Shredco, a company that destroys and recycles documents in San Antonio.I would have preferred to be an astronaut, but shredding is the family business. Even in elementary school, I helped my dad with Shredco. After I graduated high school he kept asking me to work at the company, which he had been running for more than forty years. Eventually I took over. The majority of our customers are lawyers, doctors, and accountants. Insurance companies too. Dentists are fun because a lot of times they’ve got X-rays mixed in with the paper. You’ve got to take those out if you want to be right with the…