I also agree that oatmeal and fiber is best in the morning and helps keep you full. I exercise quite often and am also constantly hungry! Sometimes it's just my mind playing tricks on me thinking I am really hungry when in fact,like you said, I am really just thirsty. Crystal Light to-go packets add a little something to your water to keep it from getting dull(lemonade and strawberry are my favorites)!
Snacking on something crunchy in between meals can eliminate cravings and help keep your meals in check to avoid overeating. For example I constantly eat carrots or snap peas throughout the day! They are refreshing and of course better yet, guilt-free!
Another great filling snack option that doesn't make you feel weighed down or too full is hummus, of course tahini-free. You can dip it in whole wheat pita bread or my favorite healthier alternative, carrots!
Happy Healthy Eating :)