1) There are several/a number of reasons/factors for my choice/pursuit ( o f...)/fondness (for...)/adaptability (to...)/concentration (on...)/advocacy (of. ..)/belief (in...) (或my seeking/choosing to do sth.)
e.g. There are several reasons for my fondness for the sports.
2) Among the factors that contribute to my achievement/choice/struggle/. .., three/a few shout louder/weigh more heavily/stand out.
e.g. Among the factors that contribute to my success in studies, three shout louder.
3) The reasons/factors/causes for my love (of...)/interest (in...)/determination (to do sth.)/objection (to sth.)/...are varied and individual.
e.g. The reasons for my pursuit of the career are varied but individual.
4) A variety of/Quite a few factors have led me to do sth.
e.g. Quite a few factors have led me to form the habit of collecting stamps .
5) My outlook (on...)/choice (of...)/participation (in...)/devotion (to...) stems from/derives from/results from some/several chief factors.
e.g. My pleasant memory of my Chinese teacher stems from several chief factors.
6) Our life/history/society abounds with/is rich in/is full of typical examples/illustrations.(e.g. 略) 7) Cases illustrative of this definition/truth/theory/principle/mechanism /saying/proverb are not rare/are too numerous to mention one by one/can be found everywhere in our life/society.
e.g. Cases illustrative of the saying—facts speak louder than words—are too numerous to mention one by one.