Feeling like I'm being left behind while everyone else is moving forward in life?

Lately, I’ve been feeling stuck while my friends and peers seem to be achieving so much, getting promotions, starting families, and reaching their goals. Meanwhile, I feel like I’m falling behind and struggling to keep up. I try to be happy for them, but deep down, I feel a sense of jealousy and self-doubt. I haven’t shared this with anyone because I don't want to seem ungrateful or bitter, but it’s been weighing on me heavily. Need advice pls.