Win a few, lose a few. That's life.
有得也有失，生活就是如此。

Let's look on the bright side.
我们来看看它好的一面。

Every cloud has a silver lining.
再黑暗的地方也有一线光明。

When god closes a door, he opens a window.
山不转水转。

Tomorrow the bird will sing.
明天会有希望的。

What you lose on the swings you get back on the roundabouts.
失之东隅，收之桑榆。
Roundabouts: adj. 迂回的 n. 迂回路线

Take it easy. You can do that.
慢慢来，你行的！