Dhammapada 1:8

The one who lives mindfully, senses under control,
Moderate in eating, devout, energetic,
Cannot be overthrown by Mara,
Such as the wind cannot shake a rocky mountain.


Keeping active not only in the mind but in body also. Moderate in eating, devout and energetic is basically saying do not give into laziness and sloth. Mara seeks to ruin a Buddha, if we keep on the middle path and do not become lazy. No matter how hard the wind blows (Mara), at the mountain (Us) it cannot be shaken.