Everybody only has one life. The second one starts when we realise that we only have one.
And
Health is like salt. You only realise when it's missing. (it refers to salt as the main spice for food so in other countries you could change it to another spice that is nearly used in all your dishes)
And
Every time people start to plan their future in the background the fate falls laughing from the chair onto the ground.
I know that's more than one but I really relate to all of them and can't decide.
"Quand on veut, on peut" = "Where there is a will, there is always a way" because that show how powerful can be an humain or a group of humain who work for their ideal. One of the most breathtaking exemple is mathematics they show how far humans can go together.
I like also "Le savoir est la clef du pouvoir" = "Knowledge is power", it's an important think: many people ignore how the knowledge is important in society.
The grass is always greener on the other side of the fence
In Russian : Хорошо там, где нас нет
Literally it translates like this : It’s good there, where we are not
Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you. Friedrich Nietzsche