Not rona, but a few years ago i was in the icu with pneumonia for 6 days. When i went back to working out I was run/walking 2 miles. Before I was sick, I was running 20 miles prepping for a marathon. Taking 2 weeks off alone is tough, add a respiratory sickness and things will only be worse. Slow down, rebuild. It'll take time, but quicker than if you were just starting from scratch.

I think your experience is shared by a lot of people who have had COVID-19, and for good reason. As you alluded to, you had been slacking off of exercising before getting sick. But when your body is infected with a virus, the immune system goes into overdrive and a lot of your metabolism is shifted to fighting it off. Hence the fatigue. There also seems to be a few things about the coronavirus which can help explain some of the longer term issues that people are experiencing. ACE receptors are in all of your blood vessels, and in your heart and in your lungs. Those tissues take a direct hit from the virus. It really isn't yet known how well people will eventually recover from the damage that the virus did to those tissues.

Anecdotal evidence is not really evidence, but here is one:

I have a neighbor who got COVID-19 in mid-March. This guy is mid-50s and I would describe him as being in very excellent shape. He worked out a ton, did not smoke, and did not drink. He was intubated and spent a total of about two weeks in the hospital. After he got home, it was probably over a month before he could even walk down to the street. He pretty much just spent his days on the front porch. His wife said he was even having difficulty remembering very simple things. Very much like a stroke patient, although his head CT showed no evidence of such. It has taken him three months to get back to close to where he was pre-COVID. Thank God he seems to be recovering completely, but some of that might be a tribute to the excellent shape he was in prior to getting sick.

It will take time. Go slowly. If you are not seeing slow but steady gains in your exercise capacity, consider getting a cardiac and/or pulmonary evaluation. All the best.
Cheers, and congrats on beating COVID.