If you don't want people to lose interest in your website quickly then you will have to spend some time focusing on your content. Unless you offer a service(such as web design or webhosting ect...) your audience will demand that there be new content updated every day for them or they will stop returning to your website. The truth is that to offer your visitors an abundance of great material is actually very easy and best yet it is free. Your site will double in value and usability when you start updating your content each day. Trust me when I say "your visitors will thank you for it".
By searching online you can easily find a wide range of websites that offer free information you can include on your website. The best yet is that the topics range from A-Z, so you never have to worry about not being able to find content for your website. Another great resource that you can find out there are free ecourses as well as free ebooks. The great thing is that you can use these free ecourses/ebooks(make sure to email each site to gain permission just to be safe) as an incentive to visitors to use your website. This will not only increase your websites content base but will give a real value to your website as it will become a known source of useful information.
As you add free content to your website keep in mind who will view it and who will use it. Make sure to cover a broad range of subjects but also direct the content according to what your website is about. Try to make your content as meaningful as you can and you will have visitors coming back each day to view what is new on your website. Best yet they will start to tell their friends and their friends will tell their friends ect.... Before you know it, by adding free content sections to your site you will have more and more people visiting your website. It is simple as that. We have all done it before where we've found a useful website and emailed the link to our friend. Why did we email the link you might ask? We've emailed the link because we found the content on the website to be useful/worth while. You can have people doing the same with your website.
Just remember to watch the content you put on your site and to make sure it is of use to your visitors. Your content will truly determined if your visitors are being entertained/interested and if they will come back for more.