When I see an acquaintance accomplishing something or achieving success, I become jealous.

Answer

As long as you don't act according to the demands of the jealousy, it will not harm you nor is it sinful as long as you restrain it. Just recite Wahoula repeatedly, and make dua for the person you are jealous. Then you will gain much thawaab for this act of mujaahadah (struggle) against the nafs. When the nafs is jealous, it demands that the person should be harmed; that you should speak bad about him; that you should make gheebat about him, etc. Resist all these demands, and you will gain thawaab, and the jealousy will then not harm you morally and spiritually. To others, speak good about the person, and when you see him, be the first to make Salaam.