Most of the time, things don't go the way you want.
Things don't go your way most of the time.
こんにちは。
様々な言い方ができると思いますが、例えば以下のような英語表現はいかがでしょうか：
Most of the time, things don't go the way you want.
Things don't go your way most of the time.
most of the time は「多くの場合」という意味の英語表現です。
「うまくいかない」は色々な言い方ができますが、今回は don't go the way you want や don't go your way としました。
ぜひ参考にしてください。
There are definitely more things that don't work out than the things that do work out.
However much effort you put into realizing your dream, it's highly likely that things don't work out as one hoped.
ご質問ありがとうございます。
① "There are definitely more things that don't work out"＝「上手く行かないことの方が断然に多い」
"than the things that do work out."＝「上手く行くことよりも。」
② "However much effort you put into realizing your dream,"＝「どれだけ夢の実現のために努力をしても」
"it's highly likely that things don't work out as one hoped."＝「願ったようにならない確率が高い。」
ご参考に。
アメリカ合衆国 
