Should really be the ball of your foot. If you are a keen cyclist then you will know about cycling shoes with cleats attached to the soles? They clip into special pedals so your feet do not move when you peal. They always place the ball of your foot on the pedals. Your legs will cease to ache when you do more cycling, try a bit every day and try to do further each time. I know I am a re-born cyclist aged 78 and I know the feeling. I think i am in my 20's but when I get to a steep hill my body tells me otherwise!