New to this

Hi! I'm super new to mountain biking so you'll have to bare with me.

Here a little info in to my scenario.

I'm a 27 year old dad who's trying to get in to shape. (Dad=budget) I'm by no means a major mountain trail dude. I live in colorado and I have access to alot of crazy tails but want to work my way up.

I ride on average about 3 to 8 miles a day just for the workout and ride on both paved trailes and hit some minor dirt trails.

Behold my Schwinn! It ain't much but it's honest work. It's my first mountain bike and I know nothing about it other than I can ride it and it was a budget option.

On to my question and don't make fun of my I'm just having fun.

Any ideas on budget upgrades that you guys would think would be worth it?