How many times have you sprinted forward to get to a drop shot or short ball, only to hit it out? Why does that happen? Because your forward momentum, and your close proximity to the net, makes it very difficult to swing slow enough to control the ball.
The solution is to bunt the ball. The bunt is basically a volley while running forward. See Punch the Volley from previous tennis tips. Let's look at the bunt.
As you run forward, your momentum provides all the power you need
Run with your racket out front and push through the ball at contact (like a volley)
Aim the ball deep if your opponent is coming in or drop shot them if they stay back
The bunt will help you control the ball when you are at a full forward run, stay in the point and up your winning percentage.