Which word or phrase in the sentence is not used correctly?

The man’s heart attack scared him badly and he decided having a regular check-up from then on.
A. Having
B. Man’s
C. Badly
D. From

If you read that sentence out loud, I'll bet you say a word in the second clause where there isn't a word written. What word do you add? Where do you add it? How would you rephrase that part of the sentence to fix this?

Let me know. =)