A patch of brick wall or letters written in a brick style font can symbolize your resilience to a life struggle. Consider having each brick shaded in red and orange ink to give dimension and texture, while the adjoining mortar can just be traditional gray. If you struggle is something tangible, such as an insulin needle for a diabetic or bottle of alcohol for an alcoholic, consider representing that object begin broken against a patch of brick wall.
While a band of barbed wire around a bicep is somewhat generic and overused, barbed wire can still be incorporated into a number of tattoo designs to signify strength. If your struggle has something to do with love or passion, consider a heart wrapped in barbed wire or even a heart constructed of barbed wire. For script, barbed wire can also be shaped into letters and words to symbolize a tattoo raw and resilient meaning.
The ocean's tide is one of the most powerful and relentless form of energy on Earth. Portraying large waves breaking against an image that represents a particular life struggle will symbolize your determination in fighting it. For instance, if you are a musician, struggling to make ends meet with your music, consider a tattoo of breaking waves against a golden musical note. Consider bright blues and greens for the waves to add a level of vibrancy to the water.
Another idea is to stamp brass knuckles over an image that represents a life struggle. Though, they may be construed as violent to some, others may see brass knuckles for their symbolic nature of fighting against the negative in your life. If the object of your struggle is too intangible to be an object at all, such as depression or loneliness, consider tattooing just the brass knuckles stamped with your name in the brass.