I found Crossing Thresholds a very helpful process for me and I wanted to give something back. I decided to get involved in mentoring as I think it's important to have a safe space, where you can talk openly to someone about your ambitions, your fears, whatever you want to discuss, without fear of being judged. And knowing that the person you are talking to is on your side and has no axe to grind, but will give you support and a different perspective.
I find it enormously rewarding, and it is a 2-way process - I have learnt a lot from people I have mentored, and it can make you re-think your position and encourages you to reflect on your own career.
I had misgivings early on as sometimes a mentee may not have a clear idea of what they want to get out of the mentoring relationship - I didn't when I was a mentee. But now I take my lead from the mentee and have seen that the safe space and chance to reflect can be helpful in and of itself, even if there isn't always a clear goal for a mentoring session. It has also worked particularly well when the mentee has had a particular goal or ask, such as help in drafting a CV or talking through competency examples for an application. I have tried to give constructive feedback on applications and CVs, so that this was an encouraging process rather than a disheartening one.
When the mentee has given me feedback, I have found it reassuring when they have indicated that the sessions are helpful! For new mentors, I would say keep an open mind, be prepared to be challenged on your thinking, relax, and remember that the mentee is probably more nervous than you are.