This sub rightfully emphasizes the importance of working out. In fact, this emphasis is the reason I started lifting three years ago. It is something that one just learns to accept as a necessary obligation in life. Recently, I have found that physically pushing your body is only half of the battle. Everyday one should not only overcome the voice inside you telling you to take a day off at the gym, but also should overcome the voice that tells you to read your book later and just browse Reddit now. The voice that says "I'm in line at the coffee shop, let me just check my phone". The voice that says "I'll do my work later, I've had a long day, let me watch some television." As one should strive to physically work out everyday, it is just as important to mentally workout. You should spend at least two hard hours forcing yourself to critically think, whether that is through your career, school, dense philosophy, or academic journals, it doesn't really matter. The truth is we all know deep down what we should be critically thinking about, and we put it off all too often.
When it comes to lift, the benefits are twofold: 1) you physically improve your strength and aesthetics 2) you feel a sense of accomplishment and confidence. The same thing is true for a mental workout. Just as one's body can decay, I have found my mind turn to slop if I do not push myself to engage with a hard mental task daily. The point of engaging in a hard mental task is to tire out your brain. It needs its exercise too, and trust me you'll sleep like a baby if you've worked it out to its limit.
So put away your phone, pick up a book. What's that hobby that you've always wanted to get into? Find the resources, and start at it. What's that topic that's always interested you as a kid? Use Wikipedia and delve in. Learn something because no one can take that away from you. At the end of the day, mental fitness is just as important (maybe more so) than physical fitness. Kill it out there; best of luck on the mental gains boys.