Fetching details from the dictionary...

keenly; deeply; fully; heartily; seriously; earnestly
calmly; quietly; softly
fixedly (gazing, staring); intently
祖父の話を聞いて人生の無常を染み染みと感じた。
I deeply felt the impermanence of life.
友の言葉が染み染みと心に響いた。
My friend's words resonated deeply in my heart.
久しぶりに帰省して故郷の景色を染み染みと懐かしんだ。
I deeply missed my hometown.