四字熟語 is literally four letters of kanji, which has meanings like proverbs. I chose some of them as examples:

一期一会: Once in a lifetime chance. It teaches that even for those we meet repeatedly, we should always think, “This may be the last time,” and cherish the moment.
日進月歩: An expression meaning that things are progressing day by day without ceasing. It teaches that it is essential to continue to work hard to achieve great goals.

獅子奮迅: To act with great vigor, as when a lioness is in hot pursuit of its prey. A person who is bold and determined in dealing with a situation. Also, it is a metaphor for the furious activity or spectacular success.
初志貫徹: It means to hold on to the aspirations and goals you set at the beginning until the end. Even if you have set your sights on a goal, as time goes by, circumstances and changes in circumstances can cause your resolve to waver. It teaches that it is crucial not to be defeated by such weakness and to carry through with the goals and aspirations that one has decided to achieve.

It’d be cool to have keychains that have your motto in them.
Let me know yours:)