Retraining on Colab
If your computer does not have an NVIDIA GPU that supports hardware acceleration of Tensorflow, traiing on your machine can be very slow. You have 2 options:
1) Train in the Cloud: this unfortunately is not free
2) Train in Colab: currently you can create GPU Colabs free. Google Colab is a Virtual Machine Environment you can use to create and run Colab (python based) Notebooks that can be used with Tensorflow to perform tasks like Data Preperation/Preprocessing, Training and Testing.