Ok, this is from my buddy, who also has a Third Class Degree Honours. What he has told me over the years sounds very true.
1. Employers will usually shortlist those who are Second Class Lower and above. Third Class Degree or General Degree are often left out. Nevertheless, it does not mean you cannot get a job. Heck, they are people sweeping the streets and still make a living. Do not think of Third Class as nothing.
2. In life, if you want to make it big, you probably cant depend too much on career. Of course, hardworking is a very positive quality and many companies would pay one person who is really hardworking to multitask, then to pay an average two person to do the same amount of job.
3. My grandpa used to say in Hokkien "How much you wear, how much you eat, how much you earn is all fated." Do not be discouraged of poor results. Make sure you can perform.
4. MOST IMPORTANT POINT, SKILLZ - How many Degree holders has the proper skills? Heck, I have classmates who cant even install Windows XP Pro when he graduated with Second Upper Honours. What does the Degree teaches us? Database design? Software analysis? Programming? Tech support? Microsoft Word even? This is also one of the many reasons, majority females who graduated in IT end up working in other fields. However, they are also very good IT-women out there, quite a few I know who are better than men.
5. NEXT IMPORTANT POINT, INTERPERSONAL SKILLZ - Believe it or not, many organization still thinks that oversea-grads and First Class grads are snobs. The management also know how to utilise manpower. To think about hiring someone First Class and hard-headed. Why not hire someone lower class Degree and bully him. This part, you gotta live with it. Because you suck at your education, you gotta make it up with hardwork. Many First Class grads usually think they are better off than other people and have poor interpersonal and social skills. Not kidding but I'm not stereotyping.
6. Since you already know you screwed up your education, then you make it up with hardwork. Like others have written, working life is a new gateway, a new life. Just like how it was before you stepped into your first day in school. It's also your LAST stage in life before you retire, so dont screw up anymore. If there is ever a time you need to work hard and get up, it's NOW!