A regular portfolio is a good practice. But I will say it is quite hard to keep record regularly since getting busier and busier. And the determination persistence is also important.
Instead of making a record of memory (it will be more precious as time passes; I do wish I have made one in my secondary school), it is a useful way for us to reflect. If there is no 'portfolio plan', we may not squeeze time to write and reflect on our experience and thinking. It may not only about the event we joined only, but it may also be a sudden thought after experiencing something or reading a book. (example: recently I have read a book called 親愛的安德烈; there are so many quotes in the book that have inspired me a lot. If I didn't write my thoughts down, I would forget this precious thinking process and lost one chance to know more on myself and thoughts; they will be very useful one day when I am having the related issue or sharing with the others)
Motivation is needed to do a regular portfolio. As an adult, I will prefer doing the portfolio by words (by article or video). Firstly, while we are translating our thoughts to words, it includes an important thinking process. Moreover, words may be more effective to reflect we thought at that moment, useful for us to look back on the past experience.
While as a teacher, I can totally understand why students are not willing to do portfolio work. Students may have much homework and portfolio is not something that can bring short-term benefit. So making students believe that it is worthwhile work, showing both short-term and long-term benefit are the most crucial but difficult part.