Some of the most common STDs include HPV, chlamydia, herpes, gonorrhea, and trichomoniasis. The four STDs that are incurable are HPV, HIV, herpes, and hepatitis. All of the others can be cured.
I disagree with the person suggesting that an average person can go 4 mph for 24 hours straight. I think average distance for an average person walking about 3.5 mph would be about 20-25 miles in a day. Then they are going to want to eat and rest.
Unsurprisingly, it's likely not a whole lot, especially since I live in Los Angeles, where nobody walks. As the New York Times explained in 2010, it is common for the health community to encourage people to walk 10,000 steps per day, which is about five miles. Researchers say it takes roughly 2,000 steps to reach a mile.