It's really a challenge for me to take this job.
这份工作对我来说确实是一个挑战。
It's really a challenge for me to chat with foreigners.
和老外交谈对我来说确实是一个挑战。
It's really a challenge for me to climb such a high mountain.
爬这么高的山对我来说确实是一个挑战。