My best way is to have a lunch break, be it 10 minutes or 45 minutes. In that time do things like your making those personal calls or make a shopping list.

Studies have shown you are actually more productive for taking a lunch break. So it's a win win and if people can't wait 10 minutes for you to have a break then they need to be reminded it's not brain surgery you are performing.
I always have lunch break is usually about 20 mins, and I sit down and have lunch (eat main meal of the day at lunchtime) in the lunch room, and chat to colleagues - maybe I need to set my alarm to go at lunchtime to remind me while I am sat there before I go back to my desk?
Other people aren't really the problem, no one is hassling me all day,(although there are totally unrealistic deadlines to be met) it is me rather than other people that are the problem - there always seems to be something I have to figure out or finish - so I put stuff off and then forget. I remember lunch because I start feeling sick if don't eat and also other people are normally going for lunch so remind me.

I do keep a list of things to do, but it is the looking at it and doing the stuff that seems to be the problem. There is zero phone reception in the room where I sit, and you have to leave the building to get the mobile to work (there is no desk phone - well we have one in the room between about 12 of us) - I think that is a contributing factor. Along with the fact I am a contractor and I get paid by the hour and have to submit my hours every week, so I suppose I am very conscious of time spent on personal things, and also there is very much the expectation of 8 working hours in the office. But I need to switch my mindset somehow.