Everyone can understand the basic concepts of stoicism. Most of them are easy to understand, but hard to apply.

Unfortunately I can not recommend any English literature, but I see Deren Browns "Happy" getting recommended a lot. The books I read all had a practical focus, trying to apply stoic ideas to day-to-day life. Most stoics will recommend to also read historical literature, like Marcus Aurelius "Meditations" - this might be a bit too much for beginners.

For me personally, the most helpful stoic idea is the "dichotomy of control". It basically says that you shouldn't worry about things or facts you can't change ("externalities") and instead focus on the things that actually are under your control. And those are VERY few things.

A trivial example: Why should I worry about the "bad" weather during my holidays? I certainly can not control the weather and by nature, the weather is neither good or bad. It's my brain that gives a sunny day more value than a thunderstorm. So instead of complaining about the weather, I should try to make the best out of it and maybe even appreciate it.

I'm 23 and took an interest in stoicism a few years back. I have to admit I didn't fully grasp the depth of it at the time, a lot of my understanding was more surface level. However having knowledge of the concepts and ideas of the rational mind from stoicism, and the idea of the differences between thoughts and feelings and our connections to them from mindfulness have both been things that I notice when I'm going about my daily life.

For instance there have been times where my mind has run away with thoughts and feelings and I've noticed that and just been able to let it go. Each time something like that has happened I've often had a feeling of 'Oh, that's what that meant.', having an awareness of the concepts of philosophy and the knowledge of people who have thought about these things before us can allow us to notice the same things within ourselves a lot easier.

I think it's worth learning about quite a lot of different forms of philosophy at a younger age, it'll allow you to be more conscious of what goes on in your head and generally understand yourself better. One thing I will say is don't try to convince yourself that you understand, only time can cement that understanding.

Definitely yes, but like all philosophies your understanding will develop as you age and your perspective changes.

Consider the book Happy by Deren Brown. It's a great summary of Ancient philosophies and then a good 'entry level' introduction to Stoicism.

As for Spinoza (idk who you were replying too), I discovered his writing at 34. It is difficult to understand at first and I had to rely on a vast quantity of vulgarisation books, podcasts, articles to be able to read and understand Ethics.

But imo it wouldn't have been harder in my 20s.

Good luck in your explorations !

Don't worry about being only 22. Lots of famous people in history did stuff at your age, and they probably also had no idea what they are doing, but did it anyways. When you're 44, you'll realise most people still have no clue, but they know how to act like they do. So just go for it! You'll figure it out on your way.

Hey, I can fondly recommend “How to be a stoic” by Massimo Pigliucci.

I really liked "A Guide to the Good Life" by William B Irvine. IMHO it not only does a good job introducing stoicism, but also a practical interpretation of philosophy.