You must gather your strength for the journey.

你必须为此次行程打起精神来。

《柯林斯英汉双解大词典》

Let us jump while we still have the strength! So, we must think of danger in times of safety and always be prepared for the worst.

趁我们还有力气，跳起来吧！所以，我们必须居安思危，未雨绸缪。

youdao

You must reserve your strength for the tennis final.

你必须为网球决赛保留体力。

youdao

A climber must have expert skill and great strength.

VOA: special.2009.01.07

But as fellow Americans, we must lend our strength to those families who have given so much for our country.

WHITEHOUSE: The White House

But as we end the war in Iraq and transition to Afghan responsibility, we must rebuild our strength here at home.

WHITEHOUSE: President Obama on the Way Forward in Afghanistan and Pakistan | The White House

In these circumstances the profession feels that it must display the strength of feeling across the country by staging this further protest action.

BBC: Lawyers stage court boycott in legal aid row