Parenting when you're ill

I'm feeling really under the weather this week and today has been the worst day so far. My mum has had the baby overnight already this week and he also spent a day with his dad's aunt so I was happy to have him with me today and didn't expect to feel worse than I did yesterday. I'm absolutely exhausted and feel totally run down and unable to really play with him as I normally would. This morning we had a play together (he woke up at 5am) and he eventually went to sleep at 10am for two hours which I also took advantage of and napped too. When he woke up we read a book and had a bit of a roll around and a chase (he loves crawling around chasing me and trying to "scare" me) and I was so weak afterwards that I couldn't even pick him up. He's been sat in his little seat in the lounge for the last 30 minutes to watching TV and I just feel awful for not being able to give him the interaction he loves and is used to.

How do you guys manage when you're feeling unwell?