If you’re just getting back to fitness, for whatever reason, start slowly.
Signing up for all of the sessions at the gym or all of the TRT sessions might seem like a good idea to give you the boost you feel you need, but too much too quickly could end in injury and an even longer layoff. Make your goal more long term, avoid quick-fixes and take it all one step at a time.
For instance, if Reading Half Marathon is your main 2021 goal, it’s more than 6 months away. That’s plenty of time to train from a standing (or sitting!) start, provided you train sensibly. Make running part of your routine again, rather than expecting yourself to do ‘what you used to do’ and don’t put too much pressure on yourself (it’s supposed to be fun, after all!).
Start by moving a little more each day. If you can, go for a walk at lunchtime (even 10 minutes is better than no minutes) or do a ‘commuter walk’ around the block, if you’re still working from home. Try to stand up and stretch for a few minutes each hour or march on the spot while the kettle’s boiling. Even these small periods of movement will help your overall health as you return to full fitness.
Unfortunately, there are no shortcuts to fitness and health: bad luck might snatch it away from you, but much of your physical health (and even your recovery from illness) is down to you.
Find the thing you enjoy and do that; running will still be here when you’re ready!