I don't know how many paragraphs your professor needs you to develop, but if your essay consists on just 3 paragraphs (introduction, body and conclusion) your thesis is OK.
Now, if your essay needs to have, lets say 4 or 5 paragraphs (introduction, body 1, body 2, body 3, and conclusion) I'd recommend you to add two more details to your essay. For example,
Schizophrenia is a severe mental illness that deeply affects not only the patient's daily life, but also his family and friends.
paragraph 1 is to develop how schizophrenia affects the patient daily life only. Paragraph 2 is to develop how schizophrenia affects the patient's family and paragraph 3 to develop how it affects his or her family.
Don't forget to put examples, professors love when you put examples.
Good luck, and if you need help, you can ask me.
F(3)=2*3-8=-2.
Hope that helps.
