Bhashya
स, य एवमेतद्गायत्रं प्राणेषु प्रोतं वेद, प्राणी भवति, अवि-कलकरणो भवतीत्येतत् ।सर्वमायुरेति, शत वर्षाणि सर्वमायुपुरुषस्य इति श्रुते ।ज्योक् उज्ज्वल सन् जीवति ।महान्भवति प्रजादिभि ।महाश्च कीर्त्या ।गायत्रोपासकस्य एतत्व्रत भवति, यत् महामना अक्षुद्रचित्त स्यादित्यर्थ ॥
In plain words
He who knows the gāyatra threaded through the vital breaths lives as breath itself, with every sense and instrument unimpaired. He attains the full span of life—a hundred years—for the scripture declares: 'The full life of a person is a hundred years.' Radiant and shining, he lives long. He grows great in progeny and great in fame. This is the vow of one who meditates on the gāyatra: that his mind remain vast and free from pettiness.
Close to the Sanskrit
He who knows thus this gāyatra woven in the breaths becomes one with breath, becomes one with unimpaired instruments. He attains the entire life span, a hundred years, for 'the entire life of a person is a hundred years' according to the śruti. Shining brightly, he lives for a long time. He becomes great through progeny and great through fame. This becomes the vow of the gāyatra meditator: that he should be magnanimous and of unpetty consciousness, this is the meaning.