Regaining fitness after travelling

Don't know where you're off to but a heart rate monitor driven program could soften the decline if you target the right zones. Could be out running, on a rowing machine or other gym kit if you have access to it. 2-3 hours a week could really help.

Aye - running is a great idea. You don't need to thrash yourself, but a 5-10k run will allow the compensating muscles in your legs to develop and the slack upper body/core muscles a good workout. I find that running keeps my knees healthier and I just feel much better for it on the bike.

The great thing is that I can pretty much stuff shorts/t-shirt into my Asics Gel Kayanos and then cram them easily into my travel bag ready for a trip with no fuss. At a pinch I've done fire-escape stair climbs as pyramids (8/12/16/12/8 flights) when the weather has been too mental for outside and there's no gym nearby.

If you have not run before - please get yourself to your local running club and they'll get you to a local good running shop to make sure you get proper shoes for your feet - which will either be supinators, neutral or over pronators and you need different shoes for each type.

My local shop is Aberdeen's Run4It which is well recommended, you'll have to find your equivalent at your local club.

Not quite answering your question but is cross-training during your 8 month travels an option? Depending on where you're going, in-line skating and cross country skiing will help you keep up your cardio as well as maintaining your quads and glutes so you'll have less of a decline to climb out of and in-line skates are pretty small, luggage space-wise. I also find that doing kickboxing year round helps not only with increasing my cardio but also lower extremity and core muscle strength (all the balance work and kicking) and it doesn't require any special equipment, just space to move around. Otherwise I suspect it will be a slow, steady slog back to your previous baseline. Just a thought.

Itll start slow but its important to be patient.start off on flat roads and keep a steady rhythm.build up your base miles,i think running really helps so i tend to do 5miles a day

Buy some running shoes.