You have to die three time by running into a low zapper obstacle without ever flying.
Just start a game and don't press anything (make sure you don't have a head start), most chances the first obstacle you'd hit will be a zapper (missiles don't appear that early), do that three times and the achievement is yours.
First of all, avoid using any vehicles, they get hard to steer pretty fast and you might pick coins by accident. So unless you are sure you can control your vehicle, either avoid picking them up or destroy them intentionally as soon as possible. In any event, turn off the magnetic vehicle add-ons if you have any.
Use powerups. Buy the Head Start powerup and when using it stay close to the ground. In my experience, 80% of the times you'll reach 750m without any coins. Grab a few Quick Revive powerups as well, use them only if you've reached a significant distance without picking any coins (say, 1250m). In the event you have a choice between death and picking up coins, die and revive yourself. I'd avoid using the Final Blast unless it's a last resort, you may end up collecting coins while you tumble away, in any case, don't use it if you have a Quick Revive unless you've used that first.
Picking up tokens is up to you, they don't count against you, and you might get a revive or a Final Blast in the slot machine, but if you use them and get coins or cash them in you'd lose your mission. I'd say - prefer to use powerups before spinning the wheel for the first time.
The mission isn't that hard, I've completed it successfully several times (I finished all missions 8 times by now), it's just takes a mixture of skill, luck and clever use of powerups.
Best Answer
You could find a more detailed explanation of the answer HERE. However, this is a basic breakdown for you.
The Gravity suit, though it does not look like one, is classified as a vehicle. And like other vehicles, it can be acquired through the same means. Through that rainbow colored gear gem like the following:
Since your chances of getting it is random, it will take some playing before you can get to it.
TIP: A handy tip would be that once you get the suit, just starting rapidly tapping the screen. Tap it 30 times and you are done.