Well you're in luck! There is a technique that was used by a gentleman called Charles Atlas, who trained himself to develop his body from that of a "scrawny weakling", to eventually becoming the most popular bodybuilder of his day.
He used a technique called dynamic tension, where he would contract his muscles isometrically, as hard as he could, such as squeezing the palms of his hands together in the position that you would end a pec-deck movement, thus giving the chest maximum resistance at the peak contraction.
This technique was effective in building strength, as well as breaking down the muscle fibers so that they could grow bigger. Best of all, it can be done almost anywhere without any equipment! Give it a try next time you have no access to any equipment (e.g. on holiday) or if you have no time (e.g. after a long day at work, while you watch TV).