Routine frustration

Hey guys I really hope someone can come and share some advice and hopefully others feeling the same as me also get some inspiration?
For context I am a young guy trying to manage independent life.
Naturally as someone with ADHD routines don’t come easy. However, I have a complete lack of structure and feel like I’m stuck in a cycle. As someone who loves the gym and exercise, being this inconsistent is so painful. I’m frustrated with how I look but also I’m almost plunging deeper into the cycle.
Work has thrown a huge wrench in the works as it’s just very tiring but I only notice it when I’m not working. Hence why my gym days are decreasing. Things I should be keeping on top on and that should support my routine cause me stress eg gym, meal prep, general cleanliness etc.
I have a lot to learn about ADHD as I’m medicated but don’t really understand why I’m like this as I keep getting more and more frustrated and sad with how I manage for myself. Any practical tips? Thanks.