I'm just going through this now. Sooner or later everyone grows old and has to go through what I'm going through now.
I'm just facing one of life's challenges a little earlier than most because everyone has to face the aging process.
次のように言うのはいかがでしょうか？
ーI'm just going through this now. Sooner or later everyone grows old and has to go through what I'm going through now.
「私は今経験しているけど、いずれみんな年をとって私が経験していることを経験しなければいけない。」
go through で「経験する」
sooner or later で「遅かれ早かれ・いつかは」
grow old で「年をとる」
ーI'm just facing one of life's challenges a little earlier than most because everyone has to face the aging process.
「みんな老化現象に直面しないといけないから、私は多くの人よりちょっと早く人生のチャレンジに直面しているだけ。」
face で「直面する」
aging process で「老化現象」
ご参考まで！
カナダ 
