Newb Training with low VO2max

Hi Joe, and welcome.
I take my Garmin VO2Max with a grain of salt, as I had a treadmill test with the mask and everything done and my numbers were a bit different. However, improvement is improvement, so if the number starts to climb, even if it isn't your exact VO2Max, it will be good for you to see it.
Without getting too technical, building your aerobic engine should be your goal, and one that will require patience. Depending on where your fitness currently is, it can take weeks, months, or even years of consistent work to show improvement. Trust me, I'm still working on it! I'm a bit advocate for doing about 80% easy, 20% hard. But even more than that, consistency is king! This article is about cycling, but I think the overall principles apply pretty well across all disciplines: https://www.wattkg.com/cycling-science/
Enjoy the ride and have fun training.

Hey Joe and welcome!

Biggest tips for someone new to endurance sports is to be consistent and take it easy starting out. A lot of new folks try to do too much too soon and end up getting injured or burnt out.

As the previous poster stated, building the aerobic engine is first priority. That’s your foundation, if it’s weak then you’re not going to be able to support the harder work.

Don’t worry about VO2 or any of that right now. The only metric I would be concerned with is time spent training. Work on gradually increasing your workouts and you will be on the right track.

That pretty much sums up the draw of endurance sports. No matter how good you get you can get better. =)

Congrats on getting off the couch! C25K is great, I used it last year to re-build after an injury.

I very much agree with the others. There's a lot of info out there. Most of it is geared for MOP (middle of the pack), or upper MOP. Some info will contradict other info. Right now your easiest improvements will come simply by training consistently.

My suggestion is to find a plan here or elsewhere on the web that fits your ability & schedule, and stick to it as best you can. By all means keep reading & learning, but trust that the plan will get you where you need to be. Jumping from plan to plan, or on each new thing you read will cause a mess.

The summer is quite a way off for a sprint, you have a lot of time to improve. You can repeat a plan 2-3 times between now and then. I like doing this because I can try out a plan to see if it works for me.

Finally you say your overweight, there's another fairly easy way to improve bike & run. When your training you need calories & nutrients to fuel your workouts, so don't go crazy with calorie restrictions. Simply using a calorie counter like My Fitness Pal or Fitbit went a long way for me when I was starting out. Being honest about what & how much I was eating opened my eyes.

Loosing weight will also put less stress on your body for running. Being overweight, be careful increasing run volume and intensity. Few things are more frustrating than getting set back due to injury.

Didn't mean to write this much, but I hope it helps.