It’s harder than you think! As a writer, it is so much easier to say, “She was sad so she sat there sobbing uncontrollably.” Often we don’t trust our reader enough. The art of good fiction is to be implicit not explicit.
Instead, try this:
It started slowly, like a volcano’s first waking shudders. The pressure in Laura’s heart surged outward in vicious waves seeking escape. A high pitched keening struck her ears. Oh god, was she making that sound? The first tear fell in a winding path. As it clung to her jaw, her lips trembled and the flood began. In between each onslaught of tears, her body shook and she gasped for air, certain these tears would drown her.