If Then Cells Controlled By Value In Cell

For a = 11 To 14
b = 10
If Cells(a, b) = 3 Then
ActiveCell.Offset(0, 0).Range("A1").Select
ActiveCell.FormulaR1C1 = "=IF(RC[-2]>0,RC[-2],"""")"
ActiveCell.Offset(2, 0).Range("A1").Select
End If
Next a

question : if i want to start the looping from the cell i am standing at instead of the defined a=11 to 14 , how ?

or

question : if i want to start the looping controlled by the cell value of the present worksheet say the value of a1 is 19 , and b1 is 30 , then it becomes : for a= 19 to 30 ,how