I'll let you into a secret.

I got access to one of the best sport strength and conditioning sites in the world. It's a members only site that contains the expertise of some of the finest strength coaches out there.

As it only cost me a dollar, I'm prepared to reveal all the secrets that lie behind the username and password box to you for nothing.

1. There is a difference between strong and athletic. Cricket, as an explosive sport, needs you to be strong and powerful but motor skills need time and effort too. There is a whole world of training methods that lie between pure strength training and pure skill work. It's best to focus on a few key movements in the gym for strength while also trying to improve balance and coordination at pace. All these elements together make up athletic cricketers.
2. No more sit ups. Ask any back doctor the fastest way to back pain and they will tell you it's because of poor posture. Most of us sit at PCs or desks a lot of the day. This hunches our shoulders and rounds our backs over time. Something the sit up and crunch just make worse. So forget that and try these core exercises instead.
3. Single leg training is better. Simply, if you train on one leg you are recreating more accurately the movements of cricket (mostly on one leg). Also, from a physical standpoint, training one leg at a time (for example, lunges) trains more support muscles in your legs and hips so gives more bang for your buck.
4. Some parts of your body need stability, some need mobility. When it comes to preventing injury, look at your body as a series of joints rather than muscles. Some need to be stable like the knee and lower back because they essentially just hold stuff in place. However the shoulder and hips need to be as mobile as possible to prevent pain in other areas.
5. Move all day, not just in the gym. We live in an increasingly static world: driving, working at computers and watching TV all require little movement. But we were made to move: it improves performance and prevents pain. The first way to do this is to work out regularly, the next thing is to get up and do stuff throughout the day. Stand up from your PC every half hour, go for a walk, mow the lawn or play with the kids/dog/significant other.
6. Plyometrics work, but you have to know what you are doing. Plyos have a bad rap for causing injury. The can do if you don't know how to do them properly. This is where most people go wrong, plunging into high level plyometrics without doing the simple stuff: Learn how to land softly first then build up the difficulty.
7. You never stop learning, especially from other areas. Nobody knows it all, no matter how much of an expert or a guru they are. It's vital to keep searching out new solutions to old questions as well as new questions. Often the answers can be found outside of the world you live in. Read lots of cricket books but read as widely as possible outside of cricket too.
8. The source of pain isn't always where it hurts. I'm not a physio or a physical therapist, but I know a bit about the field for injury prevention purposes. Often you can think you are training around pain when you are making things worse. For example, knee pain can be causes by poor hip mobility but instead of working on that, someone may stop training their lower body to stop the pain. That's self treating the site of pain, not solving the issue. If you have pain that will not go away, consult with someone who can find and stem the source.

I'll be honest; these ideas are just the tip of the iceberg. There must be hundreds of years of experience I have to draw on.