You need to be able to put the right amount of pressure on your brake pads to have them stop your car safely and effectively. When the point comes that you are feeling as if you're stepping on a sponge or have to slam your foot down extra hard to brake in time, these clear signs that your brake pedals need to be inspected and possibly repaired.
One of the most common ways that brake pedals wear down over time is by the buildup of air in the brake lines. The brake lines allow the brake fluid to flow to all of the necessary parts of the braking system. Extra air can accumulate from a blockage somewhere in the lines.
Also, you may have a crack in the line or leak that causes the brake fluid to drip out before it reaches the parts that it is supposed to lubricate.