Everyone who has played tennis for at least some time has probably noticed that on some days you're hitting the ball cleanly after few minutes but on some days it may even take over an hour! Not hitting with a clean contact in matches can easily make you lose games or even sets, depending on how long it takes to get the strokes going. So, what I'm asking is, what are the most important factors that affect the duration of this state of hitting badly? How can you get the strokes going faster? I know that if you have a match, it's a good idea to hit with a friend before the match to get the strokes going, but what if it's not an option and you still have to ensure that you'll be capable of hitting cleanly early on that day?