I always feel down when I see others accomplishing things and I feel miserable about my own achievements.

当我看到别人成功的时候，我总是感到沮丧，并对自己的成就感到痛苦。

youdao

When the people around us feel down, we usually say jiayou.

当我们周围的人情绪低落时，我们通常会说加油。

youdao

Seek help if you feel down.

心情不好时，寻求帮助。

youdao

If this should happen, the speaker might feel down in the mouth.

VOA: special.2010.06.20

First statement by Newton-- I don't feel like writing it down.

牛顿第一定律,我不想写出来

耶鲁公开课 - 基础物理课程节选

I feel the best after, basically after someone sits down and sets a goal,

基本上每个人确定一个目标的时候我感觉最好，

成为教练的理由 - SpeakingMax英语口语达人

If you perform your normal job as you would under these conditions for an entire day, it would be impossible to feel down and disengaged.

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We'd only talked for an hour, but she seemed certain, based on our conversation and the briefing she'd had with my therapist, that my body's chemistry was simply off, causing me to feel down.

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Many of us believe that when we feel down, we should try to focus inwardly and evaluate our feelings and our situation in order to attain self-insight and find solutions that might ultimately resolve our problems and relieve unhappiness.

FORBES: Do You Fall Into the Trap of Overthinking?