Going back to work after being on holiday or having time off can be hard, but there are some things you can do to help yourself ease back into normality. Organising your things the night before work can be helpful, to remove the stress that can come with an early morning. If you receive a lot of emails, you could try sorting through them gradually, instead of all at once. https://www.organdonation.nhs.uk/
Make the most of longer evenings in the summer, so that your whole day isn’t taken up by work, and do something you enjoy. Make sure you have breaks and downtime, to relax and do what you like doing; this will help to break up your day and make your free time more enjoyable. Try to exercise or go for a walk; this can help to clear your mind and reduce brain fog.
https://www.theguardian.com/money/2012/sep/03/beat-back-to-work-blues