A simple, ordinary, everyday activity. It is a constant, steady motion; not running but not standing still either. A destination is probably implied but is not necessarily the whole purpose or even the most important part of walking. If it were then we would probably choose another way to get there, one that is faster and more efficient. It is a pace that allows you to observe what is around you, to interact with those you meet along the way. It doesn't require any special skill or talent. It only requires a willingness to begin and to continue.
"Walk before me and be blameless."
This is how God chooses to state his covenant call to Abraham in Genesis 17. In other words, this is Abraham's end of the bargain; the part of the agreement with God that Abraham has to live up to. Of course, the rite of circumcision is mentioned just a few minutes later and that will become extremely important in later Judaism. But at this point in the story, circumcision is not the covenant, it is only a sign of the covenant. The covenant itself is that if Abraham will walk before God and be blameless then God will make him a father of many nations and kings and will establish this covenant as an everlasting covenant with Abraham's descendants.
The covenant is amazing in its simplicity. God doesn't give Abraham a destination to reach in a certain amount of time. God doesn't give Abraham a finite task to complete. He doesn't give Abraham certain rules to follow or ask for a list of his qualifications. He simply says "walk before me. Journey with me. Trust that I know where I am leading you even if you don't know where you are going. Live everyday knowing that I am walking with you."
And just in case the whole "be blameless" thing really gets you worried, know that most of the time in scripture this word doesn't mean perfection or sinlessness. Most often it means completion. So God isn't saying "Walk before me and I'm watching to see if you take one wrong step." After all, Abraham takes several wrong steps along the way and God doesn't abandon him. God is saying "Walk before me and see it through to completion. Live with integrity and consistency. Don't lag behind where I am leading you and don't run on ahead by yourself trying to get there without me. Keep a steady pace walking with me. Know that the journey with me is as important as the destination. And if you look up and realize that you have wandered off on your own, look around and you'll see that I'm not too far away, pointing you back to the right path.
Such is God's covenant with Abraham. Such is God's covenant with us. God calls us to a journey; a journey characterized by our continued trust in Him and the obedience and faithfulness that is the result of that trust.