Accessing variables from workspace into user-created function block in Simulink?

As the title suggests, I defined some variable say, x in the workspace that has a number. Using MATLAB function, I am trying to import that variable (just once!) and as simulation progress, under certain condition, I want to increment that variable. However, since the function does not 'see' the variable x, I end up declaring that variable inside the MATLAB Function Block. However, this keeps initializing the variable and thus, I cannot increment it. I need help to resolve this problem!