Mindfulness in the therapeutic sense is like a meditation technique that we can use in times of stress.

It's a bit dificult to describe it here on the net. I'll have a go at explaining how I use it, but there are many ways of doing it.

So, if you are feeling a bit stressed out, kinda like a storm going on around you. Find a quiet comfortable place to sit. Notice the feeling within you, notice the feelings around you. Be aware of all those feelings. So instead of denying the storm, you sit in the centre of the storm. You are safe within the centre of the storm as it whirls and twirls around you. Gradually real in the storm, that belongs to you. During the meditation process the storm/ whirlwind was let out, gradually real in the bits that belong to you. Gradually you will feel calmer, more at ease and able to go on with your work. This process can take between 10 to 20 minutes.

There are other mindfulness techniques that I use. The one above helps me, I hope this helps you too.