Imagine you were a clown and you were standing on a big colorful ball. Do you have to be aware of surroundings? Do you have to pay attention to everything and focus yourself one thing from falling off? Yes, you need to be quick to understand and to react to things Click here
Are you an on-the-fly person? Do you do things in a haste?
On the fly
On the go means busy, not stopping to rest. I've been on the go all day and I need a rest now. Check this, Something on the go!
Hope that helps!