Involvement in Competitive Programming on online judges such as Kattis, as well as in the ICPC.
In Fall 2019, as a part of an Algorithms class, an offer of bonus marks was made for any group of three in the class to participate in the Local Qualifier for the 2019 ICPC. Our aptly-named team, CMPT 360 Bonus Marks ended up winning the Advanced category, and competed in Edmonton for the Rocky Mountain Regional Qualifier. We had tons of fun, and I've participated in multiple local official / unofficial competitions since, as well as on my own in online judging systems like Kattis.
I've maintained a repository of solutions to competitive programming problems on Kattis. Generally, I use easier problems as a means to practice a particular programming language, since the solutions are not typically very deep in theory, or better in one language over another. Anything below ~3.0 is generally used to practice a language like C++.