From my experience, mentors must be: voluntary, motivated, proactive, organized to help each other, able to explain the vision and not just the tool technically. This mean you have to organize the team, train, share, discuss,… and this takes time.
In my opinion motivation is the key, because any mentor will necessarily have colleagues among their team who will be refractory to Asana, and he will have to know how to react and continue to believe what he does.
Today I have built a team of 17 people to follow up in each department, and it’s really important to keep them motivated.
Lastly, he must accept to spend some time for Asana and that their role of mentor does not always go last in their priority. But unfortunately it is necessary that the hierarchy accepts that also, or it is a little bit lost … But again, the most motivated will succeed in finding time for Asana.
Believe in your vision and your mentors team will cope with every difficulties 
