We only focus on performance goals with the added benefit of becoming better people through "suffering for challenges" (which is a horrible way to put it but being uncomfortable should be a natural feeling). It goes FAR BEYOND getting big muscles. It's about being a stronger person, physically and mentally and spiritually. Is this of any interest to you as a person? Do you want to take advantage of becoming more than a body part?
Just squat more often if you don't care about that - run hills 4 days/week. Eat. I've written an exact workout for this, on this forum, in the past 2 weeks. it's also in a bunch of books.
But I hope that you throw this idea away of associating yourself with the size of the body part and realizing physical challenges give you so much more. Wanting "big pecs" for training is like buying a race car and using it to go grocery shopping. Yeah, it's doing a job but you are missing out on 100% of what it could be.