In general, the student resume you have described is lower than those who have historically been accepted. This is not to mean there is no chance, but the stats you have provided do not tell the entire story.
1) You have time, and if you are not accepted in your first year of application, you can keep trying.
2) Would your athletic skills make you someone a Division 1 football program would seek to recruit? If so, this makes for more potential options through prep-school or direct.
3) Is your ACT an out-of-this-world score? TBD
4) The GPA is likely above 3.0 and we assume these grades are unweighted -- are you taking honors/AP/IB classes?
5) Everyone tries for a 4.0 but try and hope are not a plan for success. What you have done in the past is not working you will need to do something different to achieve something different.
If nothing changes, an unweighted and on-level High School GPA of 3.5 with a single sport as an EC with no leadership role and average performance level will find it difficult to achieve a USAFA appointment.
The great news is that you have this summer and next semester to move the needle. From a leadership perspective - you have a couple of months to demonstrate an impact in some area. From an academic perspective - I would focus on the ACT or SAT because you can make up for past transgressions academically with a rock star score. From a fitness perspective - you have football and time to practice for the CFA.