When you had fallen to the bottom of your life, every people around you would tell you: Be hard-bitten and be happy!
To be hard-bitten would be necessary, but be happy? Even in that serious occation? That would be hard for you, after all, who could keep happy while he were head-broken and bleeding.
But you should at least keep calm, calmly facing and calmly treating.
If you have obtained the calmness, without happy and without unhappy, you then have possessed the power for rebirth.