Translation of "Tougher" in Japanese

[Bear] We've done a great job making it this far, but things are about to get much tougher.

ここまでは順調だが ここからが大変になる

A human being in perfection should emulate the virtue of the tree. The more the tree grows, the more beautiful and softer it turns, but internally tougher and stronger.

模範的な人は樹の美徳を真似るべきである。育てば育つほど、綺麗で柔らかくなるが、内面的には硬くて強くなるであろう。