I have a poly classmate who went to uni subsequently and worked in the private sector before going into teaching. He always complained to me about his teaching job. He feels underpaid (when compared to his peers) and unappreciated, long hours, heavy responsibility. He typically start his day at 5.30 am and ends at about 10 pm during week days. Besides teaching and CCA, he has to do planning, set and mark papers when he gets home. Every Saturday is a half day job as well. And the discipline problems from some students and parents' complaints. He missed his days in the private sector but he find it hard to get back in after six years as a teacher.
So you have to honestly ask yourself what you want from teaching. I guess one needs to have a very strong conviction and passion if he wants to choose this path. Bear in mind, there is a 3 year bond to sign and penalty to pay if one breaks the bond, unlike in the private sector when you serve and one month notice and still get paid before you say bye bye. So, thinking carefully...