On one hand it's great that I'm finally able to lucid dream but what good is it if I'm waking up after 30 seconds or though?

The first time I started dreaming I got excited and woke up and that simply was because I got excited. The second time it happened I DID NOT GET EXCITED, I could remember telling myself to stay calm and enjoy it, but then I WOKE UP. The third time, even after staying calm, I quickly woke up.

What is happening and how can I stop myself from waking up? I know people have suggested spinning as a way to KEEP your lucid dream but what good is spinning if I don't have an indicator that I'm waking up?