Fire!

While your smoking habit has decreased your aerobic skills, and shortened your expected lifespan, at least here it can be put to good use.

Using your matches or lighter, start a line of small fires downwind of you. These fires will burn in the same direction as the approaching brush fire, but you'll be on the (relatively) safe side of them. Since everything around you is dry, it will burn through the fuel supply quickly as it passes through. Follow the fire you started as it burns a path. Once the main fire arrives, there won't be anything left for it to burn.

This technique of lighting an "escape fire" is really used by fire fighters. One of the earliest and most famous examples of using escape fires was in the Mann Gulch fire.

In 1949, a team of smoke jumpers fought a fire in Mann Gulch, Montana. For reasons not entirely understood, they became trapped and were forced to flee from an intense fire. As it became apparent the fire would certainly over take them, their foreman started an escape fire, hoping it would save him and his men by burning clear a safe area to lie in.

Unfortunately, his men were not familiar with the escape fire technique and did not understand what he was doing and continued to run. The foreman and two other fire fighters survived, but the remaining men tragically died.

Details of this even can be found at the USDA Forestry's site,Mann Gulch Fire: A Race That Couldn't Be Won and in the book by Norman MacLean, Young Men & Fire.