The Biggest obstacle is: a person must not think they will get fat if they eat more.
For the longest time I was afraid to start eating more once I started focusing on building lean muscle.
I heard people say that I had to eat more to build muscle and it was very hard because I was only taking in around 1700 calories per day. I was afraid to eat more than that cause I had used this number to lose the weight I needed to. I lost 96 pounds because of it along with exercise. I have increased my calories over time and now am eating 3,000 per day. I am 6'4, 210 pounds. I also have noticed my body becoming more and more muscular and defined. I wonder sometimes if I should be eating even more but my goal is to build lean muscle so 3,000 is pretty much ideal in my opinion. Im currently lifting an hour per day, 6 days per week along with 4 days of cardio per week. When I do cardio I go for 20-30 minutes after lifting.
People just have to come to the conclusion that you must eat. Good healthy foods of course. Carbs are very important. I guess carbs are your workers? If you don't have enough workers you can't build a physique. Protein are your bricks. Too little won't build shit and too many will be wasted.
P.S. Everyone should be eating sweet potatoes and whole wheat pasta.