Hi I am 25 years old and I have a lump on my sternum... it is not that soft or hard either and it does not hurt at all I have it almost a year now... any ideas what it could be?

It sounds like it COULD be a cyst.
Cysts are noncancerous, closed pockets of tissue that can be filled with fluid, pus, or other material. They are common on the skin but can appear anywhere, and feel like large peas (or bigger) under the surface of the skin. They can develop as a result of infection, clogging of sebaceous glands (oil glands), or around something like an ingrown hair or earring.
Their main characteristics are slow-growing, painless, and smooth to the touch when rolled.
They can be left indefinitely, but they also can become infected under some conditions.
If uninfected but you still want it gone, a doctor will just drain it.