Low blood pressure & slightly anemic - Fasting difficulties

I did 5 day fasts successfully about 2 years ago. However since then have not been able to fast more than 2 days. When I fast, I absolutely cannot concentrate on my work and I can’t do my work as efficiently. My whole brain is thinking about food non stop as well. Meanwhile, I already do have really low blood pressure and am slightly anemic so I just don’t feel well while fasting. Does anyone have tips to help me fast yet not feel so distracted and scatterbrained and unable to function? I really like the idea of fasting and hope to be more successful at it.