Wait is that speed or footwork?
If you don't have the speed or legs you used to have, try this.
Give your opponent the least possible angle of returns. This means to hit the ball to the center of the his baseline as deep as possible, no matter where you are on your side of the court. Over and over. No, it only sounds easy.
Hit the ball slow and avoid excessive topspin,
Flat is great if you can do this and clear the net by 5 to 10 feet each and every time.
Learn to do this
by doing this and don't do anything else.
Do just this! Sure, you might loose a bit but at least you're learning something that will help you win later on. A good thing.
Don't let your opponent know what you're up to. If you get a point or 2 ahead you can drop shot to his backhand side. Brake up the rhythm, If he returns that shot well don't kill yourself going after it. "Great shot." Move on.
Your opponent won't like this style of play once you master it,
by doing it. Most likely he'll start hitting harder and come to net more often. If he hits harder he'll eventually hit the ball out or into the net. Unless he's really good.
When you lob the guy, hit the lob
twice as high as you normally do. If lucky, it will carry to the base line, your opponent will be forced to hit it on the bounce just like a serve.
Discipline is important! Learn this! It'll take some time and you'll loose many matches. Learn this simple advanced technique and eventually you'll have confidence in playing this way.
Then you will have no trouble controlling the court play and you will win many matches from players you lost to before.
I spent some time writing this so I hope you do this. This training will make you a better player and you can still play as many matches as you like. Then, I'll instruct you where to go from here. If you like?
Oh, and once you master this, remember to turn your back to your opponent if you need to laugh.
J