Behold the paper walls:
While the armed forces available to NATO far outnumber those of Russia, there is a major impediment to assembling and moving those forces to the aid of NATO nations bordering Russia. That enemy is the ancient bureaucracy that controls the movement of foreign troops crossing borders, even those forces coming to your aid. This was demonstrated in early 2015 when an U.S. Army mechanized battalion made a very well publicized road march from Poland, Lithuania and Estonia back to its base in Germany. The American battalion required hundreds of hours of effort to complete the paperwork and get the permissions required to cross so many borders in military vehicles.
If only the Russians could be slowed down so easily.
Mind you, there are some good reasons for taking care when moving. A lot of bridges can't handle the heaviest NATO vehicles. So some of the paperwork is kind of necessary under the circumstances.
So NATO organized 8 small administrative units deployed in eastern Europe focused on quickly filing necessary paperwork.
That's not the Russian solution, of course.
And let me add that much of the NATO horde of troops that greatly outnumber the Russians should count themselves lucky that they can't easily reach eastern Europe. Lacking heavy armor, training, sufficient ammo and spare parts, or even basic troop physical fitness, these units would likely be slaughtered.
Sure, the Russians have problems with the bulk of their forces, too. But they would have numbers at the point of attack, some good forces to spearhead, and plenty of ammo. As long as the Russians don't have to refuel and rearm much on the way to their objectives, they'll do alright in the opening weeks of a war.
And then we'd see if NATO's ready combat units can fight through the red tape to reach the eastern front.