If your excuse is always "I'm trying," then I don't believe you.
I've always been the one to say that, so you can't fool me; I know exactly what that means. Something got into the way and you prioritized it over whatever you worked so hard on to achieve. And sometimes that's not always your fault because academics, family, and health need to come first. However, if that's your constant reason for continuously falling short, failing, and being inadequate in the things that matter to you, then you're going to need a better excuse because that's just not going to be convincing enough anymore.
You choose what matters to you: whether that be your education, religion, love life, family, social life, sports or really anything that makes up who you are. The reason they matter is because they play a part in your identity. They're important values of life you choose to focus on. But then all of a sudden you're at the threshold and you just can't get yourself to take the next step.
Maybe you've been a stellar student all your life with straight A's but now you're trying to balance hanging out with friends and completing all your homework, avoiding to pull late nighters that'll make you have bags under your eyes the morning after. Maybe you really thought he was the one or she made you feel like you were on cloud nine but after you realized that "I'll always love you" wasn't actually eternal, you're trying to move past reminiscing memories that clog up your mind for the rest of the day. Maybe you're trying to change a habit but normally is just too easy to be accustomed to.
Whatever your struggle is, we've all been in that boat and we're all trying- truly. But you need to stop trying and actually do it, you're better than your perception of "this is my best." You deserve to excel in the aspects of life that define you, make you happy. Don't let distractions crumble your identity down because slowly but surely, that's what constant "I'm trying" is doing to you. There's something that keeps getting in the way and you need to change it just for yourself. You tell yourself that you're trying your best but you don't even know your best because you have yet to reach it. And you will reach it, I promise. Just try harder.