First Marathon - Training

I entered my first marathon which is the last week in October,  I took the advise giving to start a 18 wk marathon plan.  I have being going quiet until now. Yesterday I found it a strugle to complete 5 miles. Monday and Tuesday I felt great but yesterday I found my legs extremely tired / weak. I am doing my long runs on saturdays and am a bit apprehensive now as I have 12 miles to do this week.  What can I do to help strenghten my legs. (or will they just strenghten as the miles increase) any advise is appreciated.

HEP might just be your legs are a bit knackered with the hot weather and the training. Best advice is DON'T PANIC!!!!! Could be a case of overtraining or could be anything take a deep breath and carry on with your plan if you struggle on saturday say on here and there are folks who might be able to help you ajust your plan to fit it in.

Your legs will increase as you train. Which marathon are you doing?

And can I ask which marathon training plan you're using?  I plan to run my first in January (Glouscester Marathon) but I keep on getting niggles, and while at work twisted my ankle and it's uncomfortable at the mo.

All I'm doing at the moment is working on my base fitness too! 

Thank you for hte advise.  I have entered Dublin on the 29th of October. Its is suppose to be relatively flat with alot of support along the route (fingers crossed). I decided on the Hal Higdon plan. Which has bieng quiet easy to stick to - I hope its just the heat.

Trust your body and trust the plan. Some runs are always going to be harder than others. Make sure you are well hydrated and are eating properly to help regeneration. And don't be afraid to slow down when a run feels tough. Unless you have an ambitious time goal, training is more about spending time on your feet than hitting a certain pace. I used Higdons Novice 1 to train for Dublin last year (my first marathon). It got me to the start line as it says on the tin and I crossed the finish line with a smile. Dublin is great for a first marathon. There are a few smaller hills, most notably their version of "heartbreak hill" around mile 21, but the support is truly amazing. Make sure to soak up the atmosphere and have fun.