Now most people reading this are either stuck indoors or very limited with what they can do.
Either way, don't worry if you lose form!
This is the main thing any athlete (professional or amateur) should realise. Your next race won't be for months and months.... you don't need to be burying yourself right now. You'll get bored, plateau or simply slow down in another few months... right when you should be ramping it up!
Stay active, keep turning the legs over and keep it fun.
Do different training and different sessions to make sure you don't get too bored. If you're indoors on an indoor trainer or treadmill, do sessions that you normally wouldn't do - mix together different intervals. Variety is the key!!!
Also now is a good time to work on your weaknesses.
Can't sprint? Make three of your weekly sessions based around this with short (5 - 20 second) sprints padded with ample rest (3 - 5mins of recovery).
Can't climb? If you're a cyclist and indoors, put a few books or something underneath your front wheel so you can get the position correct.
My favourite indoor bike session was always the "Devils 30".
30 x 30sec sprints with 30sec rest between each sprint. So it'll take exactly 30 minutes. It's a classic hard and exhausting session I came up with ages ago to improve my intensity. I use to do this often and also add it to athletes programs who I coach.
You're going to have a lot of time on your hands, you may as well use it!