Consider Gregor as a person. What was life like for him before his metamorphsis, both at home and on the job?
What is life like for Gregor, the protagonist of Kafka's The Metamorphosis, before his transformation?
Gregor wasn't terribly traumatized by his transformation, which is an indication that he is rather ambivalent about everything: life, work, and family. Rather than panic about his new proportions (as a large insect), he fretted about the stress of work and whether he should call in sick.
It's understandable why Gregor is ambivalent when you consider his situation. He is an adult man who has no friends, no social life, and no hobbies. He is the only wage earner in his family, and works, no only to meet their needs, but to pay off his father's debts. Even though other family members are able to work (as they begin to do as the story progresses), they refuse to do so.
Gregor does not like his job nor the people he works with and for; he looks forward to a day in some distant future when he will have worked and saved enough to pay off his father's debt and move out on his own.
Gregor's own likes and dislikes are not really known to the reader, possibly because Gregor himself can't identify them. He allows himself to be manipulated by others until his own identity is blurred. It's no wonder he is ambivalent about his metamorphosis.