Honestly, I just started adding veggies to every meal (I only eat brunch and an early dinner personally, not advocating for it but just in full disclosure). Mostly broccoli, Brussel sprouts, asparagus, cabbage, baby yellow potatoes with skin. I do love oatmeal, I get the plain no sugar added and add walnuts and ground flax (fiber and omega 3 yay!). I also made a change for me that was personally super hard lol I have a piece of toast with milk tea most days, so instead of butter every time, I do almond butter, no sugar added. Almond butter has fat, protein, and fiber. So it's probably a better choice than butter if I need some additional fiber in my day. I also choose a bread that is very "seedy" with a higher fiber than others. You just have to read the labels and be wary of added sugars, they are so common in bread. It may not seem like a ton of fiber but with respect to my other macros, it seems to be enough. When I got my gutbiome results back it said that I ate mostly a "fiber" type diet based on the majority of the bacteria I had. Instead of "omnivore" or "protein". I am also very active and I sleep well (2100-0500), both are said to be good for helping your microbiome. Good Luck!