Be willing to experience the grief. Do not fight it. Really feel the grief. This natural human emotion will evolve into another emotion when it is allowed to flow.
The flow will be inhibited if you feed the grief. This is often done by feeling self-pity, and not recognizing that it is a different feeling.
(If you find you are feeling sorry for yourself, decide whether you actually want to do that. If so, set yourself a time limit for self-pity e.g. 20 minutes, and when that time is up, choose to feel otherwise.)
Once you have the grief flowing
1. Feel it consciously as intensely as you can.
2. Put it into imaginary containers
3. Turn it all into bright sparkling light and pour it into your self