Because you only get one shot at life, you need to make the most of it.
The years pass by quickly, without the motivation to get doing something new your life will pass you by, and you will site there aged 70 thinking “is that all I have done?”
The average person has no excuses for letting this happen. The not so average people also don’t have excuses. Maybe you have a reason you can’t learn to paraglide or run a marathon, but have you a reason why you can’t do everything else on this site?
Just starting to learn one more thing, even if you don’t spend much time on it initially can be a great motivation to get on and do other stuff.
Once you have learned new skills, they quite often come in handy elsewhere.
I taught myself to swim in my lunchbreaks, not for any other reason than I just wanted to. A few years later this enabled me to join a search and rescue team, later on I was able to teach my children to swim. The knock-on effects of each skill are often not seen until years later.