If you are between the ages of 30 and 35 then you will need a stronger case for why b-school. If you are between 35 and 40 you will need a very compelling case as to why now and why not an executive program.
In general the "you're too old" argument is completely over billed and not true. At Harvard I had classmates in their 40s.
Not enough work experience is typically more the issue.