I have to press hard on the brakes to stop car on 2000 Nissan Altima

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
It started 2 days ago and it happens each time i have to brake.
(2) Answers
Most likely there's a problem with the power brake booster. It could be simple, like a collapsed vacuum hose or bad check valve, or could be something like a torn diaphragm in the booster which would then require replacement.
It could also be other problems in the brake system, like a failed master cylinder.
Get it checked ASAP, brakes are a safety item.
If you want to find a Nissan specialist, here's our directory link for you:
Qualified Local Nissan Shops
Qualified Nissan Shops For This Repair