Apart from all the great suggestions you have already got, you may consider the following:
1. Academic learning and rigor - That depends on your mindset. Normally, there is a strong negative correlation between age and ‘academic’ adaptability - and that’s why schools are reluctant to admit ppl in the higher 30’s and 40’s. But you could be among the exceptions. To confirm that, it might be better for you to first get a taste of what you will actually be going through during an MBA - The GMAT does precisely that - so it is all the more important for you as an adaptability gauge. You could also enroll in a MOOC course involving business studies - such as on coursera or edx and get a feel of what learning business subjects will be like.
2. Job Prospects - You need to be realistic about your job expectations post-MBA. Employers generally will not be looking for a profile such as yours during campus recruitments, nor would your school’s career services be able to do much. So you would have to network on your own - and it won’t be easy.
3. Application Success- You have to be very clear as to why an MBA right now? And have evidence to back your academic adaptability and employability post-mba - a good story, a great GMAT score, some additional recent academic certificates, and evidence of employability (such as your employer sponsoring the MBA), among others. No good school would want a difficult-to-be-employed candidate.
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