What makes us move? Well that's obvious. It's our feet, but how exactly does that happen. The answer is newtons third law of motion: when a force is applied to one object, that object automatically applies that same force back.
When your foot presses on the surface of the earth at an angle, the earth pushes back on your foot with the same force causing your body to accelerate forward. You might say, well then why does the earth not accelerate. That's because the earth is so big compared to your body that the force that you push on the earth with is practically nothing.
You can also tie this to conservation of momentum. If you and the earth both start at rest and a force is applied to accelerate your body, the earth body system's momentum is conserved.