Today on one of the internal MSFT agile aliases, a friend of mine asked _place_holder;and answered a question he gets all the time:
How do I become an Agile coach?
He pointed out that you can become a Certified Scrum Master by taking a course, but that you aren’t really a coach until and unless you have real experiences to back it up.
I replied to the thread with this…
My experiences mirror yours. But as you point out, not everyone can just go ├óΓé¼┼ôwork with Ward├óΓé¼┬¥. ?
Personally, I like this kind of an answer (sports metaphor intended):
You can├óΓé¼Γäót really set out to be a coach without first being a player. Get good at playing your position. Once you are good at that position, take time to learn how the other positions work. Learn how different kinds of people play different positions. Try out other positions when appropriate. Work to learn to think holistically and outside of your own comfort zone. Read a lot. Practice a lot. Talk to coaches as much as you can, and be sure to take it all with a grain of salt.
A coach is someone who can combine theory with their own unique experiences and find a way to use that to lead others to achieve success. To be a coach you have to have good communication skills, so if that is an area that needs attention, work on that too.
Finally, as with so many other leadership roles, it is important to recognize that coach is a recognition that others make of you. You can├óΓé¼Γäót be designated or self-designate yourself as a coach or a leader. When people ask you to come and help coach them, then you are a coach.
Another thing that matters a lot from my perspective is being able to be pragmatic and not dogmatic. But as Shu-Ha-Ri  teaches us, sometimes we have to start out following dogma (Shu) to better understand what is really going on underneath it all (Ha) and perhaps if we├óΓé¼Γäóre lucky achieve enlightenment (Ri).
 More reading on Shu-Ha-Ri: The Aikido FAQ, Alastair Cockburn├óΓé¼Γäós Unknowable and Incommunicable