Advice on brain cognitive health and general health

So I (female,32) have hit that wall where I start to worry about my health profusely, I've always been quite healthy conscious, always kept up with protein and always tried to keep up with my vitamin and mineral intake via food ensuring I have the right micro nutrients. However I'm starting studying again where I have to do 13 complex exams in the space of 11 months for an aerospace course

Is there any advice you guys could give regarding improving my cognitive health, focus ability and alert-ness, I'm happy to introduce vitamins and peptides (currently looking into mots-c and magnesium L-threonate) without going down the rtlin route which I'm sure would not end well 😅

I'm active, I go gym 3-5 times a week, eat pretty healthy, usually steak, chicken, salmon or lamb with kale or broccoli and up to about 4 eggs a day, I do snack on the odd chocolate bar and/or sweets too though

Thanks in advance for reading and helping 🙏🙏