How do you increase the ability to learn and reason? Like increasing working memory, long term, etc.

After the past few years of dicking around I've found out I really like just learning things - except I'm really bad at it now. I can't figure out a concept I learned a couple hours ago and apply it (it was programming and doing an exercise for it and I forgot half of it). It wasn't like that before though. That's something I could have done! I also forget things a lot more often now. Then obviously I can't recognize/remember when to use said things and I can't reason my way through them.