1. My heart is beating so fast thinking of somebody for the first time in a while.
2. I feel my heart racing thinking of somebody for the first time in a while.
1. 「胸がときめく」→そのものずばり、「my heart is beating so fast」
「誰かを想って」→「thinking about somebody」
「久し振りに」→「for the first time in a while」
2. 「自分の心臓が高鳴っているのを感じる」→「I feel my heart racing
I don’t remember when I was excited like this by thinking of someone.
It has been a long time since I felt my heart beating so fast with someone in mind.
Long time ago I felt such a racing heart beat when thinking of someone.
「誰かを思って」は
by thinking of someone
when thinking of someone
with someone in mind
「こんなに胸がときめく」は
I was excited like
I felt my heart beating so fast
I felt such a racing heart beat
「久しぶりだ」は
I don’t remember when
It has been a long time since
Long time ago
日本 
