I started a couple of months ago and am aiming for my first 5k in April. I started C25k on Endomondo .I'm reasonably fit but find it really difficult to run for over 5 minutes without stopping. I can complete 5k in 40 minutes running and walking. Ideally I'd like to run the whole race. How can increase the amount of time I can actually run? Do I just keep training 3 times a week and push myself a bit more each time?