Guess there must be something magical about being 40. I think your background should play a huge part in the decision.
The thread below has good points on career change to SAP. Career in SAP - PS at the age of 42.
https://scn.sap.com/thread/2123456
I guess if one is considering a career change to SAP at 42 so it's possible at 40.
Cheers,
Faith