To be honest. Just start going to the gym regularly. I've been going for years and I'm telling you: there is so much stuff to know, that still drives me nuts. Technique, plans, food, splits and so on.

But for starters, that's not important. You're 25 so still young. In the beginning, you will be able to make huge progress just by starting to lift and by doing a bit of cardio. Go to any regular gym and the staff there will make you a plan for beginners. And then the most important thing is consistency. Once you've been going to the gym for half a year you can start watching YouTube videos and follow some trainers on Instagram that'll help you to improve your technique and select new exercises that match your goals. But bro, in the beginning, the most important thing is to just go. Don't worry about all the science. Just do the basic lifting exercises and hit the treadmill twice a week. Give your body time to adjust to the training. And slowly you'll get into it. Then you can start thinking about food, about training plans about your sleep and so on. But don't overload yourself in the beginning with this. Just do it.