I am 46. 5ft 4ins and weigh 16 stone. 
I am a mess. I do very very little exercise and I am to the stage where I feel nervous even to walk very far, or up hill or anything really, just in case I can't cope, get breathless or bake a tit of myself. I really really desperately want and need to change. I don't want to be this unfit. I am worried about the impact of my inactivity on my health. I know it's dangerous.
Please, can anyone recommend a plan which starts with the baby steps I need to get some sort of basic fitness before I can start a proper regime?
I'd appreciate it if you didn't tell me off. I know what a twit I am for letting myself get to this stage. 
I'm looking for helpful hints. I'd rather exercise alone at this stage so that I don't have to rely on someone else being available and unfortunately I can't swim which is a pity.