But if you walk 30 minutes per day for 50 years of your life, you've already spent 9,125 hours walking, which is roughly equivalent to over a whole year of your life.
Thus, you're already down a year just from the walking. My motto about eating, exercising and death is that I'd rather enjoy my life now, than to have 5 more years of hell. Give me a nice, juicy steak any day of the week.