Don't you dare walk into the gym and just mindlessly lift. Take some time when you're repping out the sets to get your mind inside the muscle and really concentrate. If you're having trouble strengthening that mind-muscle connection, the 5-count method—lift for 5 seconds, and lower for 5 seconds—will definitely help.
Focus on having flawless form as you put your muscles to the test of time under tension. As Arnold puts it, the power of visualization is key to progress. "In my mind I saw my biceps as mountains, enormously huge, and I pictured myself lifting tremendous amounts of weight with these superhuman masses of muscle," he says. Believe and you, too, shall achieve.
Don't forget to do your cardio! Schedule it properly and you shouldn't have to spend more than 20 minutes on it.