For example, take a long walk for at least an hour,
walk up some steep hills or long distances,
this will challenge your body.
Start reading a book that has some
challenging vocabulary, long sentences
and an indepth topic, this will challenge
the way you think.
Speak with a smart person or e-mail someone
you know who is smart, try to write something
interesting and influential to them,
this will challenge your writing skills.
Do something you have never done before,
such as cook a challenging recipe or take
a dance class that will teach you a new hobby,
something that will help you, this will challenge your creative skills.

Life is about forever learning something new,
so take it on and enjoy the challenge!

By Christina

とてもクリスティーナ先生らしいコメントだと思います。
彼女自身もチャレンジングな人柄ですもの。