Chop your fruit so it is about all the same size.

In a large bowl mix together chopped fruit, sugar, and lemon juice. Let sit at room temperature for about 2 hours, stirring every so often. You want everything to get nice and juicy and the fruit to start to break down. The fresher the fruit, the faster this will happen.

After a couple of hours transfer to a large pot and bring to a boil over medium high heat. Use a potato masher to mash the fruit and get it to the consistency you desire.

Boil for 20-40 minutes, stirring frequently. Boil for 20 minutes and then start to check for doneness. You can cook until the mixture is at 220º F. Or you can test on a frozen surface. Put about a tablespoon of jam onto a frozen spoon or plate, let cook for about 15 seconds, and then run your finger through it. If it separates and doesn't run together at all, then it is done. If it is not done, cook for 5 minutes and test again.

Remove from the heat and let cool for about 30 minutes.

Transfer to clean jars or air tight containers. Place in the fridge to cool completely. If you are canning, you can do the whole canning process at this point instead of just putting it in the fridge.