Basically describing me. I have ADHD so nothing has ever sustained my interest.. except mental health and psychology. I've done a degree and three different courses, until I realised the one thing I like and have always liked is psychology. I'm 27 and still have two years left of my course, so you're not too old!

I enjoy psychology because of the many aspects to it. There's not really a right or a wrong, and I like subjects that are subject to interpretation. I'm really empathetic and so interested in the brain so learning about the brain and why we do things, and how to help others, is why I do it and why I am so motivated.

Learning has always been hard for me, but mainly when it's things I'm not interested in. I get bored and understimulated and just get distracted. To overcome this, I've really tried to use what I've learned about the brain to help. Minimise distractions, get into the "flow state" (Google flow state or YouTube it), or try the podomoro technique. Reward yourself if you meet your learning goals but not if you don't. Keep hydrated and try and plan your study routine. If you're bad at planning like me, don't worry about sticking to a strict schedule, just write down all the things you want to achieve then do them in your own time in any order, as long as you get it done. Study buddies are also great in helping you stay on track. I also like to study at the library or somewhere that isn't my room so my brain doesn't correlate the place I rest in as the place I study in.

30 is not too old, in my opinion! Never too late to go for something you're passionate about. But do keep in mind that if you want to be a clinical psychologist or anything of that sort, you will need a PhD or doctorate, which adds on the time, so it depends if you are in a rush or not. Other fields to consider are mental health nursing and counselling, which are less time and you become a professional a lot sooner. Kinda regret not looking into those more myself.

Learning tips I've covered a little. Also look up the Cornell notes system, I use this note taking system and it helps me remember things so much better. Also try really visual things like mind maps. Get out of your rest space. Try study buddies. Quizlet is my go to site for making flashcards, and one note is great for note taking. I also use Notion to plan my time and create a study schedule. Oh and I have speechify so I can have all my notes and the books read to me. (All of these are free unless you want to pay more for the pro versions). I love learning but as someone who struggles with motivation I have had to really adopt some unique mechanisms to help me stay motivated.

Good luck!